skydive vs sky dive

skydive and sky dive both are verbs.

Word	Noun	Adjective	Verb	Adverb
skydive	No	No	Yes	No
sky dive	No	No	Yes	No

As verbs, skydive and sky dive are synonyms defined as:

skydive and sky dive: jump from an airplane and perform various maneuvers before opening one's parachute

skydive (verb)	sky dive (verb)
jump from an airplane and perform various maneuvers before opening one's parachute	jump from an airplane and perform various maneuvers before opening one's parachute