any unknown, variable, or unspecified factor, number, person, or thing
2. chemistry
atomic number
3. physics
impedance
4.
zone
5. currency
zaïre
abbreviation for
6.
Zambia (international car registration)
z's in American English
(ziz)
noun
(used with a plural v.) slang (often used withgrab, catch, etc.)
sleep
to grab some z's before dinner
Also: Z's
Word origin
[1960–65; from the conventional use of a series of z's to represent snoring]This word is first recorded in the period 1960–65. Other words that entered Englishat around the same time include: bicycle kick, deinstitutionalize, parvovirus, pop art, tag question