length vs skip distance

length and skip distance both are nouns.

Word	Noun	Adjective	Verb	Adverb
length	Yes	No	No	No
skip distance	Yes	No	No	No

As nouns, skip distance is a hyponym of length; that is, skip distance is a word with a more specific, narrower meaning than length:

length: size of the gap between two places
skip distance: the shortest distance that permits radio signals (of a given frequency) to travel from the transmitter to the receiver by reflection from the ionosphere

Other hyponyms of length include leg, arm's length, gauge, light time, wingspan, wingspread, wingspread, altitude.

length (noun)	skip distance (noun)
a section of something that is long and narrow	the shortest distance that permits radio signals (of a given frequency) to travel from the transmitter to the receiver by reflection from the ionosphere
the linear extent in space from one end to the other; the longest dimension of something that is fixed in place
continuance in time
the property of being the extent of something from beginning to end
size of the gap between two places