Smallcombe is an English locational surname originating from South West England, particularly the West Country counties of Wiltshire, Devon and Somerset. Small is a description of size and combe is a local word meaning cleft or valley (cf Welsh 'cwm' and Celtic 'cumb'). A 'small combe' is, then, a geographical feature and combe is found in many place names in South West England.
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Smallcombe Wikipedia(Text) CC BY-SA