L.
_Langdon._ _Loing_, of ships; _dion_, a harbor. A harbor of ships.
_Leahy._ _Leat́an_, pronounced _leahan_, wide; _an_, denoting personality. A large person.
_Lillagan._ _Lile_, genitive of _lil_, lily; _gan_, offspring. Descendant of a lily.
_Limerick._ _Luimneać_, from _luime_, or _loime_, bareness; _neać_, for _na eać_, of the horses. Bareness of the horses. The original possessor of this name was, doubtless, a native of the town of the same name, which was built on a peninsula made bare by the many horses sent thither to graze.
_Linn._ _Linn_, a marsh, a swamp.
_Linnehan._ _Linn_, a marsh; _leat́an_, wide. A broad marsh. Linahan and Linehan are from the same roots.
_Linch._ _Leat́-inse_, _leat́_, half; _inse_, island. Half-island. Lynch has like derivation.
_Linton._ _Linn_, a marsh; _ton_, from _tun_, Anglo-Saxon for town. A town built on a marsh.
_Loch._ _Loć_, pronounced _loch_, _lokh_, _logh_, a lake.
_Long._ _Long_, a ship. Not to be mistaken for the Anglo-Saxon _long_, or _lang_, having length. The typical Longs were of Celtic origin.
_Loughlin._ _Loć_, lake; _linn_, a marsh. A lake within a marsh.
_Loughry._ _Loć_, lake; _riǵ_, pronounced _reegh_, or _reey_, king. The lake of the king. Lowry, an abbreviation of the name.
_Lunn._ _Luan_, the moon.