extend vs cross

extend is not a noun while cross is a noun.

Word	Noun	Adjective	Verb	Adverb
extend	No	No	Yes	No
cross	Yes	Yes	Yes	No

As verbs, cross is a hyponym of extend; that is, cross is a word with a more specific, narrower meaning than extend:

Other hyponyms of extend include span, sweep, traverse, sweep, overlap, overspread, spread, ridge, constellate, dot, stud.

extend (noun)	cross (noun)
	(genetics) the act of mixing different species or varieties of animals or plants and thus to produce hybrids
	(genetics) an organism that is the offspring of genetically dissimilar parents or stock; especially offspring produced by breeding plants or animals of different varieties or breeds or species
	a wooden structure consisting of an upright post with a transverse piece
	a marking that consists of lines that cross each other
	any affliction that causes great suffering

extend (adjective)	cross (adjective)
	extending or lying across; in a crosswise direction; at right angles to the long axis
	annoyed and irritable

extend (verb)	cross (verb)
extend one's limbs or muscles, or the entire body	breed animals or plants using parents of different races and varieties
thrust or extend out	trace a line through or across
extend in scope or range or area	travel across or pass over
lengthen in time; cause to be or last longer	meet and pass
continue or extend	meet at a point
expand the influence of	fold so as to resemble a cross
increase in quantity or bulk by adding a cheaper substance	hinder or prevent (the efforts, plans, or desires) of
prolong the time allowed for payment of	to cover or extend over an area or time period
use to the utmost; exert vigorously or to full capacity
open or straighten out; unbend
extend or stretch out to a greater or the full length
cause to move at full gallop
offer verbally
make available; provide
span an interval of distance, space or time
reach outward in space
stretch out over a distance, space, time, or scope; run or extend between two points or beyond a certain point