Synonyms of the word

apathetic

• adj. Void of feeling; not susceptible of deep emotion; passionless; indifferent.
• adj. Of, or pertaining to apatheism.

indifferent

• adj. Not caring or concerned; uninterested, apathetic.
• adj. Mediocre, usually used negatively in modern usage.
• adj. Having no preference or bias, being impartial.
• adj. Not making a difference; without significance or importance.
• adj. (mechanics) Being in the state of neutral equilibrium.
• adv. (obsolete) To some extent, in some degree (intermediate between very and not at all); moderately, tolerably,…

spiritless

• adj. Lacking energy, drive, motivation or emotion. Enervated.

uninterested

• adj. (obsolete) Unmotivated by personal interest; unbiased, disinterested.
• adj. Not interested; indifferent, not concerned.