string vs language unit

string and language unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
string	Yes	No	Yes	No
language unit	Yes	No	No	No

string (noun)	language unit (noun)
a lightweight cord	one of the natural units into which linguistic messages can be analyzed
a tie consisting of a cord that goes through a seam around an opening
a necklace made by stringing objects together
a tightly stretched cord of wire or gut, as a part of an instrument or a tennis racket
a collection of things threaded on a single strand, or as if threaded on a single strand
stringed instruments that are played with a bow
a linear sequence (as of characters, words, proteins, etc.)
a sequentially ordered set of things or events or ideas in which each successive member is related to the preceding
(cosmology) a hypothetical one-dimensional subatomic particle having a concentration of energy and the dynamic properties of a flexible loop
a tough piece of fiber in vegetables, meat, or other food (especially the tough fibers connecting the two halves of a bean pod)

string (verb)	language unit (verb)
add as if on a string
provide with strings
thread on or as if on a string
remove the stringy parts of
string together; tie or fasten with a string
stretch out or arrange like a string
move or come along