Antonyms of adj irresistible

2 senses of irresistible

Sense 1
irresistible (vs. resistible), resistless -- (impossible to resist; overpowering; "irresistible (or resistless) impulses"; "what happens when an irresistible force meets an immovable object?")

resistible (vs. irresistible) -- (capable of being resisted or withstood or frustrated; "a resistible attack"; "such resistible temptations")

Sense 2
irresistible -- (overpoweringly attractive; "irresistible beauty")

INDIRECT (VIA attractive) -> unattractive -- (lacking beauty or charm; "as unattractive as most mining regions")

Similarity of adj irresistible

2 senses of irresistible

Sense 1
irresistible (vs. resistible), resistless -- (impossible to resist; overpowering; "irresistible (or resistless) impulses"; "what happens when an irresistible force meets an immovable object?")
       => overpowering, overwhelming -- (so strong as to be irresistible; "an overpowering need for solitude"; "the temptation to despair may become overwhelming"; "an overwhelming majority")

Sense 2
irresistible -- (overpoweringly attractive; "irresistible beauty")
       => attractive (vs. unattractive) -- (pleasing to the eye or mind especially through beauty or charm; "a remarkably attractive young man"; "an attractive personality"; "attractive clothes"; "a book with attractive illustrations")