/ ˈɜːtʃɪn; NAmE ˈɜːrtʃɪn/ noun
1.
( old-fashioned ) a young child who is poor and dirty, often one who has no home :
a dirty little street urchin
2.
= sea urchin
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WORD ORIGIN
Middle English hirchon , urchon hedgehog , from Old Northern French herichon , based on Latin hericius hedgehog.