Of, from, or pertaining to Tonga, the Tongan people or the Tongan language.

(uncountable) An Austronesian language of the Polynesian branch spoken in Tonga. / (countable) A person from Tonga or of Tongan descent.

plural of Tongan

(uncountable, sometimes derogatory, slang) A notional system of time which others sometimes derogatorily ascribe to Tongans, and which they sometimes jocularly ascribe to themselves, to account for their supposed tendency to be leisurely, not rigorous about scheduling, and often tardy.