Other forms: scariest, scarier
Scary means making people feel fear. A scary film, a scary moment, it was scary.
It is informal and very common in speech. Frightening is the neutral word and terrifying is the strong one. Note the -y and -ed pair, which behaves like the -ing and -ed pairs: a scary film makes you scared. Scared takes of for a lasting fear — scared of dogs — and by for a particular fright. And scary is one of a small set of adjectives, with silly and pretty, whose comparative changes the y to i: scarier, scariest.
1adjectivescaryMaking people feel afraid.
“It is a scary film and not a good one.”
synonyms: frightening, terrifying, creepy
2adjectiveworryingWorrying in a way that is hard to control.
“The speed it spread was the scary part.”
Too few real examples of this word to estimate which sense is commonest.
scary is a quality of causing fear.
Also accepted in games: frightening
From scare + -y.
Etymology from Wiktionary, CC BY-SA