chiefly British English spelling of analyze (q.v.).
Analyse is better than analyze, but merely as being the one of the two equally indefensible forms that has won. The correct but now impossible form would be analysize (or analysise), with analysist for existing analyst. [Fowler]
c.1600, "to dissect," from French analyser, from analyse (see analysis). Literature sense is attested from 1610s; meaning in chemistry dates from 1660s. General sense of "to examine closely" dates from 1809; psychological sense is from 1909. Related: Analyzed; analyzing.