Sneaky describes someone who does things quietly, behind your back, hoping you will not notice. The colleague who reads your screen the moment you stand up; the child who lifts a biscuit out of the tin with one hand pressed on the lid so it will not rattle.
It is a milder word than dishonest — sneaky is about the method, not the size of the crime. Half its uses are almost affectionate: a sneaky look at the answers, a sneaky cigarette outside the back door, a sneaky extra biscuit. In sport it turns into praise, because a sneaky pass is one nobody saw coming. The adverb is sneakily, the noun is sneakiness, and the verb sneak gives you sneak out, sneak in, sneak a look. A sneak is also the child who runs to the teacher, which is the opposite kind of behaviour under the same word.
1adjectivesneakyDoing things quietly and secretly so as not to be seen, in a way that seems dishonest.
“It was sneaky of him to read the letter while she was out of the room.”
2adjectivedoneDone quickly and quietly for your own pleasure, without anyone noticing.
“We had a sneaky ice cream before dinner and told nobody.”
3adjectivecleverlyCleverly deceptive, in a way people admire.
“That was a sneaky little pass through two defenders.”
Proto-Germanic
*snīkaną — to creep, crawl
Proto-West Germanic
*snīkan
Old English
snīcan — to creep, crawl
Middle English
sniken — to creep, crawl
English
sneak
English, today
sneaky
From sneak + -y. sneak Possibly from Middle English sniken (“to creep, crawl”), from Old English snīcan (“to creep, crawl”), from Proto-West Germanic snīkan, from Proto-Germanic snīkaną (“to creep, crawl”), of origin; compare formally unrelated snake, snoop, snook, snoke and snoot. Cognate with Danish snige (“to sneak”), Swedish snika (“to sneak, hanker after”), Icelandic sníkja (“to sneak, hanker after”). Possibly related to a doublet of snitch.
Etymology from Wiktionary, CC BY-SA