NEGATIVE PREFIXES
1-2. A-/AnThese Greek-derived prefixes mark words expressing an absence
of something (atypical, anodyne). A- is attached to words starting
with consonants, and an- is the form for words beginning with
vowels. An exception is words beginning with h; depending on the
root word, either prefix may be present (ahistorical, anhydrous).
3. AntiAnti-, from Greek by way of Latin, means “opposite” (antithetical) or
“in opposition to” (antivirus), and can also denote defense
(antisubmarine) or prevention (antidepressant).
4. DisThis Latin prefix, when attached to a word, implies one of several
meanings: absence (disaffected) or lack (disabled), opposition
(disapprove), or removal (disenfranchise).
5. InIn- and its several variations, all signaling Latin derivation, also
denote lack of a given quality. The variations il- and -ir are attached
to words starting with l or r (illogical, irreversible). Im-, meanwhile,
precedes m (immaterial) and p (impatient) and the lone example for
b: imbalance. The rare prefix ig- sometimes comes before n
(ignoble). In- appears before root words beginning with all other
letters.
6. NonThis Latin negative prefix is the least particular of the class, and can
often be found attached to root words so that the resulting term
differs in meaning from one formed by the attachment of another
negative prefix to the same root word. For
example, nonrational means “not according to rational means or
rules,” but unrational refers to behavior that does not conform to
these norms. The nonparticular non- is the go-to negative prefix for
neologisms.
7. UnBy contrast with the other negative prefixes, the attachment of this
Latin-based form to a root word can, in addition to expressing lack
or absence (unconcern), denote a reversal (uncoiled). It can also
refer to an action not yet taken (unopened).