also: ろくずっぽ · ろくすっぽう
adverb
(not) properly; (not) well; (not) enough
Colloquial adverb used with a negative verb to mean 'not properly', 'not well', or 'hardly at all'. Stronger and more emphatic than ろくに.
See also: ろくに
彼はろくすっぽ勉強もしないで試験に落ちた。
He failed the exam without studying properly at all.
He left without even a proper greeting.
ろくに is the standard adverb meaning '(not) properly', while ろくすっぽ is a more emphatic, colloquial variant used in the same negative constructions.
Derived from ろくに with an emphatic suffix すっぽ of uncertain origin, possibly a sound-symbolic addition.