eye cup vs eyecup

eye cup and eyecup both are nouns.

Word	Noun	Adjective	Verb	Adverb
eye cup	Yes	No	No	No
eyecup	Yes	No	No	No

As nouns, eye cup and eyecup are synonyms defined as:

eye cup and eyecup: a small vessel with a rim curved to fit the orbit of the eye; use to apply medicated or cleansing solution to the eyeball

Other synonyms of eye cup include eyebath.

eye cup (noun)	eyecup (noun)
a small vessel with a rim curved to fit the orbit of the eye; use to apply medicated or cleansing solution to the eyeball	(embryology) a two-walled cuplike depression that develops into the pigmented and sensory layers of the retina
	a small vessel with a rim curved to fit the orbit of the eye; use to apply medicated or cleansing solution to the eyeball