under the weather vs seedy

under the weather and seedy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
under the weather	No	Yes	No	No
seedy	No	Yes	No	No

As adjectives, under the weather and seedy are synonyms defined as:

Other synonyms of under the weather include ailing, indisposed, peaked, poorly, sickly, unwell.

under the weather (adjective)	seedy (adjective)
somewhat ill or prone to illness	full of seeds
	morally degraded
	somewhat ill or prone to illness
	shabby and untidy