This topic is unusual in that all the affixes that I will mention in it are prefixes. Most prominent are re- and the negative or ‘reversive’ prefixes un-, de- and dis-, as in the following examples:

(31) paint, enter                       repaint, re-enter

(32) tie, tangle                          untie, untangle

(33) compose, sensitize           decompose, desensitize

(34) entangle, believe              disentangle, disbelieve

The prefix re- has already figured in our discussion of the relationship between morphemes and meaning. Semantically, the examples in (31)–(34) are mostly straightforward, although those with de- are less so: to decompose is not to undo the creative work of a musical composer!

Also worth mentioning here is the relationship between the verbs in the left and right columns in (35):

(35) Intransitive                    Transitive

        LIE (past lay)                  LAY (past laid)

        RISE (past rose)             RISE (past raised)

        FALL (past fell)               FELL (past felled)

        SIT (past sat)                  SET (past set)

Transitive verbs (or verbs used transitively) are ones with an ‘object’ noun phrase, usually indicating the thing or person that is the goal of the action of the verb, as the book is the object of laid in (36a). Intransitive verbs, such as lay in (36b), lack such an object.

(36) a. Jill laid the book on the table.

        b. The book lay on the table.

The transitive verbs in (35) are all causative, that is they mean ‘cause to X’, where X stands for the meaning of the corresponding intransitive. Causative–incausative verb-pairs are common in English, but they nearly all involve conversion, as in (37), rather than either affixation or the kind of vowel change seen in (35):

(37) a. Jill boiled the water.

        b. The water boiled.

The examples in (35) represent a residue of a vowel-change pattern that was more widespread at an earlier stage of the language. More will be said about such historical developments.