Real Dictionary

-tic in American English
suffix: a suffix, equivalent in meaning to -ic, occurring in adjectives of Greek origin (analytic), used esp. in the formation of adjectives from nouns with stems in -sis

tic
countable noun: If someone has a tic, a part of their face or body keeps making a small uncontrollable movement, for example because they are tired or have a nervous illness.

tic in American English
any involuntary, regularly repeated, spasmodic contraction of a muscle, generally of neurotic origin
noun: a sudden, spasmodic, painless, involuntary muscular contraction, as of the face

tic in British English
noun: spasmodic twitching of a particular group of muscles