(idiomatic) A thing or situation which is almost certain to eventually lead to an accident

(idiomatic) A greeting, usually for birthdays, in reference to the passing year; Happy birthday!

(biochemistry) Any of a group of antibacterial, antimycotic and antialgal alkaloids isolated from the blue-green alga Hapalosiphon fontinalis.

plural of hapalindole

(simile, colloquial) Very happy (sometimes with the extra connotations of being carefree or unaware of grimmer realities).

Alternative spelling of trigger-happy

Ellipsis of hapax legomenon.

(Britain) A children's card game played with a pack of 44 picture cards that depict a father, mother son and daughter of 11 families mostly having occupational surnames (e.g. Mr Bun the Baker); players have to collect entire families

(chiefly UK and Ireland, idiomatic, vulgar, simile) Extremely happy; obviously satisfied and carefree.

(literature) A clichéd conclusion in which all loose ends are tied up and all main characters are content.