Other forms: urchins
An urchin is a ragged, mischievous child of the streets. Dickens is full of them.
The word is dated and always slightly literary, and it carries poverty in it rather than simple naughtiness, which is why street urchin is close to a fixed phrase. The other meaning is a sea creature, since a sea urchin is the spiny ball that lives on rocks and hurts anyone who stands on it. The two are connected, because urchin is an old word for a hedgehog, and the sea urchin was named for looking like one.
An urchin was a hedgehog. Middle English irchoun meant a hedgehog and a sea urchin alike, from Latin ērīcius, and the sea creature keeps the older sense exactly.
Latin
ērīcius
Vulgar Latin
*ericio
fro-nor
heriçun
Middle English
yrchoun
English, today
urchin
Built from
From Middle English yrchoun, irchoun (“hedgehog; sea urchin”), from fro-nor heriçun, from Vulgar Latin ericio, from Latin ērīcius. Compare modern French hérisson, whence the English doublet a doublet of herisson.
Etymology from Wiktionary, CC BY-SA