sudden, unexpected, rapid, surprising, quick, rash, curt, brief, short
abrupt: blunt, brisk, short, snappy, rude, sharp, sudden, hurried, surprising, quick converse: contrary, opposite, reverse
Both are correct.
Synonym means: a word having the same or nearly the same meaning as another in the language. Definition means: the act of defining or making definite, distinct, or clear / the formal statement of the...
He is a pronoun. The only synonym it has is to use the name of the person it refers to, i.e., "He is short." "John is short."