Most alacritous is a phrase used to describe someone who is very enthusiastic, eager, and quick in doing something. The antonyms for this phrase include sluggish, lethargic, indolent, and sluggishness. A sluggish person moves slowly, lacks energy or enthusiasm, and is often lazy or unproductive. Lethargic people are inactive, slow to move or think, and lack motivation or excitement. Indolent people are idle, disinclined to work or exertion, and are generally inactive. Whereas, sluggishness refers to a lack of energy, drive, or motivation, which can cause someone to be slow or unresponsive. All these antonyms signify the opposite of most alacritous and are used in different contexts to describe a person's behavior or attitude.