also: やーだ
interjection
Strong, often childish or informal refusal or denial. Equivalent to いやだ with a more casual, emphatic feel.
「一緒に宿題やろうよ」「やだ、めんどくさい」
"Let's do homework together." "No way, it's a pain."
やだ、そんなの絶対に嫌だ。
No, I absolutely hate that.
interjection
Expression of disgust, dismay, or strong dislike. Often used by children or in casual, emotional reactions.
やだ、ゴキブリがいる！
Eew, there's a cockroach!
やだ、雨降ってきた。
Oh no, it started raining.
Contraction of いや (disagreeable) + だ (copula). 'from いや + だ'.