What is a prefix?

As you can see, the highlighted segments (un-, i-) give the radical a new meaning when they are joined to it. This segment is a morphic unit known as prefix.In this way, we can say that the prefix is ​​the morphic element that appears before the stem and gives it a new meaning..

In Portuguese, the prefixes have two origins: Latin and Greek. From their union with the stem, new words are derived. See in the table below what these prefixes are:

Latin origin prefixes

Prefix	Sense	Example
ab- abs- The-	separation, separation	abdicate, abort
ad- The- air- at-	approach, direction	adjacent adept, attachment, approach, enroll
before-	anteriority	anticipate, forearm
circum- (circum-)	move around	circumscribe circumpolar
cis-	short position	cisalpine, cisatlantic
co- with- con- color-	contiguity, company	cohabit, supporting condone to contain correlation
against-	opposition, joint action	contradict, nonsense, act together
in-	top-down movement, reduction	decay, ebb, decrease
un-	separation, contrary action	undo, divert, dig up
dis- di- right-	separation, movement to different sides, denial	to dissolve spread settle
in between-	middle position	between the lines, clash
ex- s- and-	outward move, previous state	export drain emigrate
extra-	outer position (out of)	unofficial, misplace
in- im- i- in- en-	inward movement	inference immigrate break out pocket to board
in- im- i- go-	denial, deprivation	unhappiness waterproof illegal irreparable
intra-	inner position	intracontinental intravenous
intro-	inward movement	introduce introversion
fair)-	position beside	juxtapose juxtafluvial
w- O-	forward position, opposition	obstruct to occur
per-	move through	go through, drill
post-	posterity	postpone, postgraduate studies
pre-	anteriority	predisposed prehistoric
pro-	forward movement	progress propel
re-	backward movement, repetition	to resort, replicate redo
retro-	backward movement	go back retrograde
soto- under-	inferior position	general sota sotopor wing
sub- sus- su- under only-	bottom-up movement, inferiority	go up, underling suspend succeed survive uplift
super- about-	position up, excess	superimpose overcrowded overlap
above-	position above, excess	above, above
trans- rear- tra- three-	movement beyond, position beyond	transpose translate tradition crazy sleepless
ultra-	position beyond the limit	overtake, ultrasound
vice vis- (vizo-)	replacement, instead of	vice dean viscount

Prefixes of Greek origin

Prefix	Sense	Example
a-N-A-)	deprivation, denial	illiterate, anemia, atheist
a-N-A-	reverse action or movement, repetition	anachronistic, anaphylactic, anaphora
host	on both sides, around	amphibian, amphitheater
after-	separation, separation	apogee, apostate, apotheosis
archi- arc- arch- arch-	superiority	archduke, arch-millionaire archangel archetype archbishop
pick-up	top down movement	catalog, catalepsy, catadupa
morning- di-	movement through, removal	diagnosis, diocese
dis-	difficulty, bad condition	dyspnea, dysentery
eh- ex-	outward movement	eczema exoderm
en- in- and- endo- end-	inward position, inward movement	brain Ellipse endothermic endosmosis
epi-	superior position, posterity	epicenter epidermis epigenesis
me- ev-	well good	euphemism, euphoria gospel
hyper-	top position, excess	hyperbole, hypertension
hippo-	inferior position, scarcity	hypodermic hypotension
goal- met-	posterity change	metacarpal, metamorphosis
for- pair-	proximity, next to	paradigm, parasite
peri-	position or movement around	perimeter, periphrase
pro-	forward position, previous	prologue, prognosis
yes- yea- si-	simultaneity, company	symphony, sympathy, syllable.

By Mariana Rigonatto
Graduated in Letters

Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/portugues/o-e-que-prefixo.htm