Polharrow is a Gaelic name formed from the wordspoll 'stream' and airbhe 'wall, fence'. The Scotswordburn has been added later, when the meaning of poll in the name became opaque. The wordairbhe is also found in Loch Harrow. It is not clear if the loch gave rise to the name of the burn or vice versa. Maxwell proposed a derivation meaning 'the bull's burn', taking the second element to be thairbh 'of a bull'. This derivation is considered to be 'unlikely'.