Antonyms of adj vigorous

2 senses of vigorous

Sense 1
vigorous -- (characterized by forceful and energetic action or activity; "a vigorous hiker"; "gave her skirt a vigorous shake"; "a vigorous campaign"; "a vigorous foreign policy"; "vigorous opposition to the war")

INDIRECT (VIA energetic) -> lethargic, unenrgetic -- (deficient in alertness or activity; "bullfrogs became lethargic with the first cold nights")

Sense 2
vigorous -- (strong and active physically or mentally; "a vigorous old man who spent half of his day on horseback"- W.H.Hudson)

INDIRECT (VIA robust) -> frail -- (physically weak; "an invalid's frail body")

Similarity of adj vigorous

2 senses of vigorous

Sense 1
vigorous -- (characterized by forceful and energetic action or activity; "a vigorous hiker"; "gave her skirt a vigorous shake"; "a vigorous campaign"; "a vigorous foreign policy"; "vigorous opposition to the war")
       => energetic (vs. lethargic) -- (possessing or exerting or displaying energy; "an energetic fund raiser for the college"; "an energetic group of hikers"; "it caused an energetic chemical reaction")

Sense 2
vigorous -- (strong and active physically or mentally; "a vigorous old man who spent half of his day on horseback"- W.H.Hudson)
       => robust (vs. frail) -- (sturdy and strong in form, constitution, or construction; "a robust body"; "a robust perennial")