breathless vs dyspnoeic

breathless and dyspnoeic both are adjectives.

Word	Noun	Adjective	Verb	Adverb
breathless	No	Yes	No	No
dyspnoeic	No	Yes	No	No

As adjectives, breathless and dyspnoeic are synonyms defined as:

breathless and dyspnoeic: not breathing or able to breathe except with difficulty

Other synonyms of breathless include dyspneal, dyspneic, dyspnoeal.

breathless (adjective)	dyspnoeic (adjective)
not breathing or able to breathe except with difficulty	not breathing or able to breathe except with difficulty
appearing dead; not breathing or having no perceptible pulse
tending to cause suspension of regular breathing