Compared to English, knowledge of prefixes and suffixes will help your vocabulary even more in Latin, because about 85% of Latin words are secondary, containing a prefix and/or suffix(es). Here are some general notes, which you may want to read through and refer back to from time to time as you go through the rest of the material.

        Prefixes and suffixes are easier to learn after you have learned enough words having them to have a knowledge basis to build on. For a pre-test to see what you know (and which ones you need to work on) or as a review after you have studied the individual prefixes/suffixes, you can go to the general Word Formation Exercises.

Prefixes

1.  Prefixes are adverbial and the translations may, therefore, be somewhat different from the translations of the prepositions that they correspond to.  Chart.

2. Some prefixes (e.g. re-, se-) are “inseparable,” and are only used as prefixes; there are no corresponding prepositions.

3. Some prefixes are more complex and have multiple meanings; some of these meanings do not seem to correspond to translations of the preposition.

4. Many English derivatives are based on Latin words with prefixes (and suffixes). Often the meaning of the English derivative may help you. Sometimes, though, the prefix has become productive in English, and the proportions of the different meanings and uses may not be the same as in Latin. Sometimes, thus, the English may lead you astray in interpreting the meanings of Latin words.

5. The general rule in Latin is that you translate the verb root first, then the prefix (backwards, just as you translate the personal subject ending and tense marker, then the root). If needed, you can then adapt this literal translation to fit the context.
Note: Compound verbs often take the dative. Translate the verb root first, then any accusative direct object (if the root is transitive), then the prefix, then any dative.
e.g. anteponō: I put (acc. ____) before (dative ______). Prefixes that may take the dative have a * in the chart below.

6. Sometimes when a prefix is added, the vowel of the verb root will “weaken,” (e.g. cap- > -cip). For the chart, see chart below (and Linguistic Rules #13).

7. The form of the prefix will sometimes change or assimilate (ad + similo, -are, cf. similis) to go with the beginning of the verb stem that follows.
e.g. ad +  capiō > accipiō.
Note: The prefix ab does not assimilate; if there is an assimilated prefix beginning with a- and a double letter (e.g. ac-c, al-l), it is from ad, not ab.

8. Sometimes a “d” is added between a prefix ending with a vowel and a verb root beginning with a vowel. e.g. re + eō >  re-d-eō.

9. Most prefixes are added to verbs. One (in- as negator) is added only to adjectives (and their corresponding adverbs), and others may be added to adjectives sometimes or adjectives may be formed from verbs with a prefix. See below for in- (+ adjective/adverb)

10. Some compound verbs are better learned as separate vocabulary words. Analyzing them will often lead to inappropriate or incorrect translations, e.g. inveniō, pereō.  The most frequent ones will also be indicated under the sections with their respective prefixes. (Note: The only “exceptions” that remain in languages are ones that are frequently used. These are worth learning, therefore.)  Remember the general rule when analyzing/guessing the meaning of words: it must make sense in the context and it must fit the grammatical function of the form of the word in the sentence.

11. Some compound verbs are more frequent than the simple, basic verb.  One of these verb roots does not occur as a simple verb in Latin. This is the verb *dho (cf. Greek τιθημι), which means “put, place.” It comes out in Latin looking the same as dō, give. Both are usually 3rd conjugation in compound verbs. Compare: reddō (I give back) and condō (I put up, found, establish).
Sometimes the original meaning of the simple verb is more common in compound verbs, whereas the simple verb develops a more common metaphorical or secondary meaning.

12. Verbs that have a reduplicated perfect form, do not always have a reduplicated perfect when in a compound.
e.g.  currō, pft. cucurrī,
but incurrō, pft.  incurrī.

Some reduplicate, but the “e” of the reduplication weakens to “i” (cf. 6 above and chart below):
e.g. dō, pft. dedī
reddō, pft. reddidī

Some reduplicate the consonant, but do not include the vowel:
e.g. pellō, pft. pepulī,
repellō, pft. reppulī

cadō, pft. cecidī
recidō, pft. reccidī

13.  Sometimes the preposition (in a prepositional phrase) and the prefix seem to be redundant. The preposition is obviously necessary, so why is the prefix needed on the verb? Sometimes the longer verb form is preferred to or more common than the shorter (e.g. the verb eō go, linquō, scandō). Sometimes the compound form has a slightly stronger or different meaning than just the stem plus the preposition. Sometimes it may be for emphasis or as a reminder.

Translations of Prefixes

Group	Frequency		Preposition	Prefix	Example
		ā / ab	(away) from; (+ person): by	away	ā-mittō; ab-sum
		*ad	to	toward, to; near	ad-veniō
		*ante	before, in front of	before (especially of time)	ante-ponō
		*circum	around	around
		*cum	with	con- together; completely; (forcefully) Prefix page
		de	(down) from; about, concerning	down
		dis- / dī-		in different directions, apart, away; not
		ē / ex	out of; (out) from	out:  Prefix page exceedingly
		*in	in, on; into	(+ verb) in, on
				in- (+ adjective) not; un- Prefix page
		*inter	between; among	between
		*ob	on account of	against; towards; opposite
		per	through	through; thoroughly, through and through Prefix page
		*post	after;  behind	after
		*prae-		ahead; before; in front of
		pro	for; in front of; instead of, . . .	pro(d)- forth, forward Prefix page
		re(d)-		back; (back again; back againstPrefix page
		*sub	under	under; (from) under; somewhat; secretly
		*super	over, above	over
		trāns	across	across

* Compound verb may take a dative. See  # 5 above.

For more prefixes, not occurring on the most frequently used words, see the Word Formation page.

Vowel Weakening

i < a:  in short syllable (before a single consonant or -ng)
per-ficiō < faciō

e < a:  in long syllable (before two or more consonants)
captus < capiō
inceptus < incipiō

i < e:  in short syllable (before single consonant)
con-tineō < teneō

ī < ae:
re-quīrō < quaerō

ū < au:
in-clūdō < claudō For more on vowel weakening, see Linguistic Rules.

For more information and practice exercises on particular prefixes, click on the link in the chart above. 

Suffixes

Suffixes change the part of speech of a word, e.g.timeō (verb) > tim-or (noun). Noun-making suffixes are the most numerous. Some are used when forming a noun from a verb stem as opposed to an adjective stem. Some noun suffixes are used to indicate a person, some an abstract concept, and some a thing or result. Knowledge of these suffixes helps interpret the meaning of unknown words, as well as what declension (and, therefore, ending) a noun or adjective is. Besides noun and adjective suffixes, there are also adverb and verb suffixes.

1. Many words are formed by adding a suffix (e.g. -(t/s)iō, -(t/s) to or (4th declension nouns) are based on the supine (4th principal part) stem of
a verb. To identify the (present) verb that they are from, use the same guidelines as for identifying perfect passive forms: (see Principal Parts and Linguistic Rules)
-sus stems < present stems in -d or -t:  vīs-iō < vīs-us (from _____)
cas-us (from ______)
voiced consonants change to unvoiced before (unvoiced) -tus
-ctus stems may < present stems in -g:    ac-tor < act-us (from ______)
-ptus stems may < present stems in -b:    scrip-tor < script-us (from _____)
a nasal infix (-n-) drops in the perfect. It is only in the present sysstem.
vic-tor < vict-us (from vi_cō)
tact-us (from ____; where did the -c- come from?)

2. Some verb suffixes (such as -scō) occur only in the present system (present/future/imperfect). The suffix does not remain on the perfect stems.
cogni-tiō < cognit-us (from _______ with vowel weakening)