noun: (pharmacology) An antispasmodic and anticholinergic drug C₂₂H₃₁NO₃ administered transdermally as a skin patch or orally in the form of its hydrochloride C₂₂H₃₁NO₃·HCl to relax the smooth muscles of the bladder in the treatment of urge incontinence, frequent urination, and urinary urgency.