Astray means away from the right path or the right course. Go astray, lead somebody astray, the letter went astray.
It works literally for things that get lost in the post and morally for people led into trouble, and the moral sense is much the older. Lead astray is nearly always about somebody young being influenced by somebody worse.
1adverbastrayAway from the right path or the right course.
“We went astray in the fog and ended up on the wrong side of the hill.”
astray is a direction.
Old French estraier, to stray, from a Latin phrase meaning to wander beyond bounds. Stray is the same word.
Latin
extra — beyond
Medieval Latin
extravagari — to wander beyond
Old French
estraier — to stray
Middle English
astraien
English, today
astray
Built from
From Middle English astraien or by apheresis straien, from Old French estraier (“to stray”), from late Medieval Latin extravagari (“to wander beyond”), from Latin extra (“beyond”) + vagārī (“to wander, stray”).
Etymology from Wiktionary, CC BY-SA