Adjectives derived from adjectives

In this category, prefixes predominate. The only suffix of note is -ish, meaning ‘somewhat X’, as in GREENISH, SMALLISH, REMOTISH ‘rather remote’. By contrast, the prefix un- meaning ‘not’ is extremely widespread: for example, UNHAPPY, UNSURE, UNRELIABLE, UNDISCOVERED. Because it is so common, most dictionaries do not attempt to list all un- adjectives. This does not mean, however, that un- can be prefixed to all adjectives quite freely; we do not find, for example, ‘UNGOOD’ with the meaning ‘bad’ (though George Orwell included that word in the Newspeak vocabulary devised for Nineteen Eighty-Four).

Another negative prefix is in-, with allomorphs indicated by the variant spellings il-, ir- and im-, as in INTANGIBLE, ILLEGAL, IRRESPONSIBLE and IMPOSSIBLE. It is more restricted than un-, largely for historical reasons. For the present, it is worth noting the existence of pairs of more or less synonymous adjectives, one of which is negated with un- and the other with in- or one of its allomorphs:

(22)    eatable/uneatable                    edible/inedible

            readable/unreadable              legible/illegible

            lawful/unlawful                        legal/illegal

            touchable/untouchable          tangible/intangible

Such examples confirm that the use of in- is lexically restricted. As the negative counterpart of EDIBLE, UNEDIBLE sounds possible, especially if the speaker has limited education and has not encountered, or has momentarily forgotten, the form INEDIBLE. However, ‘INEATABLE’ as the counterpart of EATABLE is not a form that any English speaker would spontaneously use.