Bawnboy takes its name from the term "bawn", the defensive wall surrounding an Irish tower house. It is the anglicised version of the Irish word "badhún" meaning "cattle-stronghold" or "cattle-enclosure" – its original purpose was to protect cattle during an attack. The remains of a late medieval bawn is to be seen at Bawnboy House, which is the origin of the village name. The earliest surviving mention of the placename is in the 1663 Hearth Money Rolls for Templeport where it is called "Baonboy". Another name for the village is Kilsub or Kilsob.