Webster's Revised Unabridged Dictionary · 1913

Peradventure

Peradventure , adverb and conjunction

[Old English per aventure, French par aventure. See Per, and Adventure.]

By chance; perhaps; it may be; if; supposing.
If peradventure he speak against me. — Shakespeare
Peradventure there be fifty righteous within the city. — Gen. xviii. 24

Peradventure , noun

Chance; hap; hence, doubt; question; as, proved beyond peradventure. — South