柏 'cypress / pine resin' +
油 'oil / tar' +
路 'road' - literally 'cypress-oil road'. The character
柏 is read bǎi here (in
柏油 'asphalt / coal tar') but bó in surnames (
柏林 'Berlin') and as the wood name. The compound originally referred to coal tar derived from pine and cypress wood, before petroleum-based asphalt took over.
