quiddity

[kwid-i-tee] /ˈkwɪd ɪ ti/
noun, plural quiddities.
1.
the quality that makes a thing what it is; the essential nature of a thing.
2.
a trifling nicety of subtle distinction, as in argument.
Origin
1530-40; < Medieval Latin quidditās, equivalent to Latin quid what + -itās -ity
British Dictionary definitions for quiddity

quiddity

/ˈkwɪdɪtɪ/
noun (pl) -ties
1.
(philosophy) the essential nature of something Compare haecceity
2.
a petty or trifling distinction; quibble
Word Origin
C16: from Medieval Latin quidditās, from Latin quid what
Contemporary definitions for quiddity
noun

the real nature or essence of something which makes it different from others

Word Origin

Latin quid 'something' + -ity

noun

a subtlety or quibbling point; triviality

Word Origin

Latin quid 'something' + -ity

Word Origin and History for quiddity
n.

"a trifling nicety in argument, a quibble," 1530s, from Medieval Latin quidditas "the essence of things," in Scholastic philosophy, "that which distinguishes a thing from other things," literally "whatness," from Latin quid "what," neuter of indefinite pronoun quis "somebody, someone or other" (see who). Sense developed from scholastic disputes over the nature of things. Original classical meaning "real essence or nature of a thing" is attested in English from late 14c.