- without interest, vigor, or determination; listless; lethargic: a lackadaisical attempt.
- lazy; indolent: a lackadaisical fellow.
- lacking vitality and purpose
- lazy or idle, esp in a dreamy way
adj.1768 (Sterne), from interjection lackadaisy “alas, alack” (1748), an alteration of lack-a-day (1690s), from alack the day (1590s). Hence, “given to crying ‘lack-a-day,’ vapidly sentimental.” Sense probably altered by influence of lax. Related: Lackadaisically.