ðə sˈɛkənd pˈɑːɹt ʌvðə nˈeɪm ɪz ɐ lˈɔst stɹˈiːmnˈeɪm, aɪdˈɛntɪkəl ɪn ˈɔːɹɪdʒˌɪn tə ðə tˈæɹəz wˈɔːɾɚɹ ɪn dʌmfɹˈiːsʃɚ, dᵻɹˈaɪvd fɹʌmðə bɹɪʔˈn̩ɪk ɹˈuːt ˈæstɚɹˌɪsk tˈɑː, "mˈɛltɪŋ, θˈɔːɪŋ, dɪsˈɑːlvɪŋ", sˈʌfɪkst wɪð ˈɑːɹ ɐn ˌædʒɪktˈaɪvəl sˈʌfɪks kˈɑːmən ɪn ɹˈɪvɚnˈeɪmz, plˈʌs ˈɛs, ðə skˈɑːts plˈʊɹɹəl.
The second part of the name is a lost stream-name, identical in origin to the Tarras Water in Dumfriesshire, derived from the Brittonic root *tā, "melting, thawing, dissolving", suffixed with -ar an adjectival suffix common in river-names, plus -s, the Scots plural.