godan verb (-su), intransitive verb
let out a cry; shout out; burst out yelling
Describes suddenly starting to shout or cry out, often involuntarily or with strong emotion.
驚いて思わず叫び出した。
I was so surprised that I let out a cry without thinking.
彼は痛みのあまり叫び出した。
He burst out yelling from the pain.
Standard kanji spelling.
Variant with だす in kana; common in informal writing.
叫ぶ is the base verb meaning 'to shout' or 'to scream'; 叫び出す adds the nuance of suddenly starting to shout or breaking into a cry.
Compound of 叫び (continuative form of 叫ぶ, 'to shout') + 出す (auxiliary verb meaning 'to start' or 'to burst out').