Antonyms of adj vacillant

1 sense of vacillant

Sense 1
vacillant, vacillating, wavering -- (uncertain in purpose or action)

INDIRECT (VIA irresolute) -> resolute -- (firm in purpose or belief; characterized by firmness and determination; "stood resolute against the enemy"; "faced with a resolute opposition"; "a resolute and unshakeable faith")

Similarity of adj vacillant

1 sense of vacillant

Sense 1
vacillant, vacillating, wavering -- (uncertain in purpose or action)
       => irresolute (vs. resolute) -- (uncertain how to act or proceed; "the committee was timid and mediocre and irresolute")