chiefly British English spelling of analyze (q.v.), which was the former spelling there (as in Johnson's dictionary). In 17c. analize also was used.
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]
"the theory or therapy of treating mental disorders by investigating unconscious elements and bringing repressed fears and conflicts to the patient's awareness," from Psychoanalyse, coined 1896 in French by Freud from Latinized form of Greek psykhē "the soul, mind, spirit; understanding" (see psyche) + German Analyse, from Greek analysis (see analysis). Freud earlier used psychische analyse (1894).
Meaning "statement presenting results of an analytic process" is from 1660s. Psychological sense is from 1890. English also formerly had a noun analyse (1630s), from French analyse, from Medieval Latin analysis. Phrase in the final (or last) analysis (1844), translates French en dernière analyse.