Nouns

(n)quarterlya periodical that is published every quarter (or four issues per year)

Adjectives

(a)quarterlyof or relating to or consisting of a quarter“quarterly report”

Adverbs

(r)quarterlyin diagonally opposed quarters of an escutcheon“two coats of arms borne quarterly”
(r)quarterly, every quarterin three month intervals“interest is compounded quarterly”