Formal words and the plainer words that usually do the same job.
accentuate→stress, highlight
accompany→go withFPLG
accomplish→do, carry out, finishFPLGaccomplished as an adjective (skilled) is fine
accordingly→soFPLG
accrue→build up, gainFPLGkeep in accounting
accumulate→collect, gather, build up
acquire→get, buy
additional→more, extraFPLG
additionally→also
adequate→enough
adhere→stick, follow
advantageous→helpful, usefulFPLG
advise→tell, recommendFPLG
advocate→support, urge, backthe noun is fine
aforementioned→this, these
aforesaid→this, that
alleviate→ease, relieve
allocate→give, assign, divideFPLG
ameliorate→improve
amidst→amid
amongst→among
anticipate→expectFPLG
apparel→clothes, clothing
apparent→clear, plainFPLG
appreciable→noticeable, largeFPLG
apprehend→arrest, catch, grasp
apprise→tell, inform
appropriate→right, proper, suitableFPLG
approximate→roughFPLG
approximately→about, around
ascertain→find out, learnFPLG
assist→help
assistance→help
attain→reach, meetFPLG
attempt→tryFPLGas a noun, attempt is fine
attire→clothes
attributable→due
augment→add to, increase
beneficial→helpful, good
bestow→give, grant
beverage→drink
capability→abilityFPLG
cease→stop
cessation→end, stop
circumvent→get around, avoid
cognizance→awareness, notice
cognizant→aware
collaborate→work together
commence→start, beginFPLG
commencement→start, beginningkeep for graduation ceremonies
commensurate→in line, matching
compel→force, makecompelling (persuasive) is fine
component→partFPLGkeep in software and engineering
comprehend→understand
comprehensive→full, complete
comprise→include, make upFPLG
conceal→hide
conceptualize→imagine, picture
concerning→aboutFPLG
concur→agree
conflagration→fire
consequently→soFPLG
consolidate→combine, mergeFPLG
constitute→make up, formFPLG
construct→buildthe noun is fine
contemplate→consider, think about
convene→meet, call togetherFPLG
converse→talkthe converse (the opposite) is fine
correspondence→letters, mail
culminate→end, peak
currently→nowFPLGoften you can cut it
deem→consider, thinkFPLG
deficiency→lack, gap, flawkeep in medicine
deficient→lacking, short
deleterious→harmful
delineate→outline, describe
demonstrate→show, proveFPLG
denote→mean, show
depart→leaveFPLG
depict→show, describe
designate→name, chooseFPLG
desire→want, wishFPLG
determine→decide, find outFPLGdetermined as an adjective (resolute) is fine
detrimental→harmful
diminish→shrink, reduce, lessen
disburse→pay, pay out
discern→see, tell, notice
disclose→reveal, tell, showFPLG
discontinue→stop, endFPLG
disseminate→spread, share, sendFPLG
domicile→homekeep in legal text
dwelling→home, house
effectuate→carry out, cause
efficacious→effective
elevate→raise, lift
eliminate→cut, remove, endFPLG
elucidate→explain, clarify
emanate→come, flow
encompass→include, cover
encounter→meet, find, faceFPLG
endeavor→tryFPLGas a noun, use effort or attempt
enhance→improve
ensue→follow, result
ensure→make sureFPLG
enumerate→list, countFPLG
envisage→imagine, expect
envision→imagine, picture
equitable→fairFPLG
eradicate→wipe out, end
erroneous→wrong
erroneously→wrongly, by mistake
establish→set up, createFPLG
evident→clearFPLG
evince→show
exacerbate→worsen
exceedingly→very
exhibit→showFPLGkeep the noun for shows and court evidence
expedite→speed up, hurryFPLG
expeditious→fast, quickFPLG
expend→spend, useFPLG
expenditure→spending, cost
expiration→endFPLG
expound→explain
fabricate→make, buildif it means lie, say invent or make up
facilitate→help, easeFPLG
feasible→possible, workableFPLG
finalize→finish, completeFPLG
forfeit→lose, give upFPLG
forthwith→at once, now
frequently→oftenFPLG
furnish→give, send, supplyFPLGkeep when it means fitting out with furniture
henceforth→from now on
herein→here, in thisFPLG
heretofore→until nowFPLG
herewith→here, with thisFPLG
hitherto→until now, so far
identical→sameFPLG
immediately→at once, nowFPLGfine when you need the emphasis
impart→give, pass on, tell
impede→slow, block, hold up
impending→coming, near
imperative→vital, urgentkeep in grammar and programming
implement→carry out, do, startFPLGkeep in software, where it is the usual term
inadvertently→by mistake, accidentally
incentivize→encourage, reward
inception→start, beginningFPLG
incorporate→include, addkeep for forming a company
indebtedness→debt
indicate→show, sayFPLG
individual→personthe adjective is fine
inebriated→drunk
inform→tell
initial→firstFPLG
initiate→start, beginFPLG
inquire→ask
inquiry→questionkeep for formal investigations
instantaneously→at once, instantly
institute→start, set upthe noun is fine
insufficient→not enough
interrogate→question, ask
juncture→point, stage
leverage→usekeep in finance (borrowing)
locality→place, area
magnitude→sizeFPLGkeep in science
mandatory→required
manifest→showthe noun (cargo list) is fine
maximum→most, largestFPLG
merchandise→goods
methodology→methodFPLGkeep when you mean the study of methods
minimize→reduce, cutFPLG
minimum→least, smallestFPLG
mitigate→reduce, ease, lessen
modify→changeFPLG
monitor→watch, check, trackFPLGthe noun (a screen) is fine
necessitate→need, call for, forceFPLG
nevertheless→still, even so
nomenclature→names, terms
nonetheless→still, even so
notify→tellFPLG
notwithstanding→despite, stillFPLG
numerous→manyFPLG
obfuscate→hide, confuse, muddlekeep in programming
objective→aim, goalFPLGthe adjective (unbiased) is fine
obligate→bind, requireFPLG
observe→see, watch, noticeFPLG
obtain→get
oftentimes→often
operate→run, work, useFPLGkeep for surgery
operationalize→carry out, use
optimal→bestkeep in math and engineering
optimize→improvekeep in technical writing
optimum→bestFPLG
originate→start, come
ostensibly→seemingly, apparently
parameter→limit, settingFPLGkeep in math and programming
paramount→main, chief, vital
partake→take part, share
participate→take part, joinFPLG
perform→doFPLGkeep for stage performances
permissible→allowed
permit→let, allowFPLGthe noun (a license) is fine
perpetuate→keep alive, continue
peruse→read, look over
plethora→glut, excessa plethora of means many
portion→part, shareFPLG
posit→suggest, propose, claim
possess→have, ownFPLG
practicable→workable, possibleFPLG
preceding→earlier, previous
precipitate→cause, triggerkeep in chemistry
preclude→prevent, rule outFPLG
predominantly→mostly, mainly
preliminary→first, early
preponderance→bulk, most
presently→now, soonambiguous; say now or soon
previously→before, earlierFPLG
principal→main, chiefkeep for a school head or a loan's principal
prioritize→rank, focus onFPLG
proceed→go, go ahead, continueFPLGproceeds (money) is fine
procure→get, buyFPLG
proffer→offer
proficiency→skillFPLG
proficient→skilled, good
prohibit→ban, forbid
proliferate→spread, grow, multiply
promulgate→issue, publishFPLG
propensity→tendency
provide→give, offerFPLGfine when it means supply; give is often plainer
proximity→nearness
purchase→buyFPLGas a noun, purchase is fine
rectify→fix, correct
regarding→about, onFPLG
reimburse→repay, pay back
reiterate→repeat, restate
relinquish→give up, hand over
relocate→moveFPLG
remainder→restFPLGkeep in math
remediate→fix
remuneration→payFPLG
render→make, giveFPLGkeep in graphics and web code
replicate→copy, repeatkeep in science and databases
request→ask, ask forFPLGas a noun, request is fine
require→needFPLGfine for rules and requirements
requirement→needFPLG
reside→liveFPLG
residence→home
resultant→resulting
retain→keepFPLG
salient→main, key
scrutinize→examine, check
selection→choice, rangeFPLG
signify→mean, show
solely→only
solicit→ask for, seekFPLG
stipulate→state, require, set
strategize→plan
subsequent→later, nextFPLG
subsequently→later, thenFPLG
substantial→large, muchFPLG
substantiate→prove, support
sufficient→enoughFPLG
sufficiently→enough
supersede→replace
supplementary→extra, added
tantamount→equaltantamount to means equal to
terminate→end, stopFPLG
thereafter→after that, then
thereby→so, by doing this
therefore→soFPLG
therein→there, in itFPLG
thereof→its, of itFPLG
thusly→thus, like this
timely→promptFPLG
totality→whole
transmit→sendFPLG
transpire→happen
ubiquitous→everywhere, common
undertake→do, take on
utilization→use
utilize→use
validate→confirm, checkFPLGkeep in software for input checks
viable→workable, practicalFPLG
voluminous→large, bulky
warrant→justify, call forFPLGthe noun (legal order) is fine
whereby→by which, so that
wherein→in which, where
whilst→while
witness→seeFPLGthe noun is fine