Antonyms of adj happy-go-lucky

1 sense of happy-go-lucky

Sense 1
carefree, devil-may-care, freewheeling, happy-go-lucky, harum-scarum, slaphappy -- (cheerfully irresponsible; "carefree with his money"; "freewheeling urban youths"; "had a harum-scarum youth")

INDIRECT (VIA irresponsible) -> responsible -- (worthy of or requiring responsibility or trust; or held accountable; "a responsible adult"; "responsible journalism"; "a responsible position"; "the captain is responsible for the ship's safety"; "the cabinet is responsible to the parliament")

Similarity of adj happy-go-lucky

1 sense of happy-go-lucky

Sense 1
carefree, devil-may-care, freewheeling, happy-go-lucky, harum-scarum, slaphappy -- (cheerfully irresponsible; "carefree with his money"; "freewheeling urban youths"; "had a harum-scarum youth")
       => irresponsible (vs. responsible) -- (showing lack of care for consequences; "behaved like an irresponsible idiot"; "hasty and irresponsible action")