Of persons or their dispositions: Having the mental attributes characteristic of the sanguine complexion (see sense A. 3 above); chiefly, disposed…

= elastic, adj.

figurative. Of the spirits: Easily recovering from depression, elastic, light. Of persons: Light-hearted, cheerful, hopeful.

figurative. Of feelings, temperaments, etc., hence, also, of persons: Not permanently or easily depressed; buoyant.

figurative. Of a person, the mind, etc.: tending to recover quickly or easily from misfortune, shock, illness, or the like; buoyant, irrepressible…

(perhaps) cheerful in the midst of difficult circumstances.

Of a person or action: displaying or characterized by a cheerful lack of concern about the future; easy-going.

toujours gai/ɡe/, ‘always cheerful’; cheerful under all circumstances; also as n., an unfailingly cheerful disposition. Occasionally partially…

That bounces; having a buoyant manner.

colloquial (originally and chiefly U.S.). Cheerful, happy; hopeful, optimistic, positive; lively, vigorous.

= blue-sky, adj. (in various senses).