poorly vs sickly

poorly and sickly both are adjectives.

Word	Noun	Adjective	Verb	Adverb
poorly	No	Yes	No	Yes
sickly	No	Yes	No	No

As adjectives, poorly and sickly are synonyms defined as:

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

poorly (adjective)	sickly (adjective)
somewhat ill or prone to illness	somewhat ill or prone to illness
	unhealthy looking

poorly (adverb)	sickly (adverb)
(`ill' is often used as a combining form) in a poor or improper or unsatisfactory manner; not well