'Irresistible' definitions:

Definition of 'irresistible'

From: WordNet
adjective
Impossible to resist; overpowering; "irresistible (or resistless) impulses"; "what happens when an irresistible force meets an immovable object?" [syn: irresistible, resistless] [ant: resistible]
adjective
Overpoweringly attractive; "irresistible beauty"

Definition of 'Irresistible'

From: GCIDE
  • Irresistible \Ir`re*sist"i*ble\, a. [Pref. ir- not + resistible: cf. F. irr['e]sistible.] That can not be successfully resisted or opposed; superior to opposition; resistless; overpowering; as, an irresistible attraction. [1913 Webster]
  • An irresistible law of our nature impels us to seek happiness. --J. M. Mason. [1913 Webster]

Synonyms of 'irresistible'

From: Moby Thesaurus