Antonyms of adj wishy-washy

1 sense of wishy-washy

Sense 1
namby-pamby, gutless, spineless, wishy-washy -- (weak in willpower, courage or vitality)

INDIRECT (VIA weak) -> strong -- (having strength or power greater than average or expected; "a strong radio signal"; "strong medicine"; "a strong man")

Similarity of adj wishy-washy

1 sense of wishy-washy

Sense 1
namby-pamby, gutless, spineless, wishy-washy -- (weak in willpower, courage or vitality)
       => weak (vs. strong) -- (wanting in physical strength; "a weak pillar")