Cuil Rathain has been interpreted as 'the corner of the ferns'. The other and more probable translation of the town name, based upon 'cuil rath na ene' is 'little fort on the corner' referring to the prominent ancient earthen rath at Mountsandel, situated on a very distinct bend of the River Bann near the Salmon Leap.
The Red Cross is the cross of St Patrick who is claimed to have given Coleraine its name, Cul Rathain. The blue lines on each side of the cross represent a port or harbour, of which there are four in the Borough. The wheat sheaves represent agriculture in the Borough, whilst the fish denotes the salmon found in the River Bann.
The castle on top of the shield refers to the former 11th-15th century Norman Castles as well as to the 16th-17th century earthen ramparts of the planned town. The dragons supporting the crest originate from the City of London Arms. Only settlements granted Borough status or better are permitted to have supports of this kind.