Etymology
Advertisement
variable (n.)

"quantity that can vary in value," 1816, from variable (adj.) in mathematical sense of "quantitatively indeterminate" (1710). Related: Variably; variability.

Related entries & more 
Advertisement
variable (adj.)

late 14c., of persons, "apt to change, fickle," from Old French variable "various, changeable, fickle," from Late Latin variabilis "changeable," from variare "to change" (see vary). Of weather, seasons, etc., attested from late 15c.; of stars, from 1788.

Related entries & more 
alphanumeric (adj.)

"using both letters and numbers," 1912, contracted from alphabet + numeric (see numerical).

Related entries & more 
exponential (adj.)

"of or pertaining to an exponent or exponents, involving variable exponents," 1704, from exponent + -ial. As a noun in mathematics from 1784. Related: Exponentially.

Related entries & more 
Advertisement
Cepheid (n.)

type of variable star, 1904, from Delta Cephi, the name of the first such star identified, which is in the constellation Cepheus. With -id.

Related entries & more 
invariable (adj.)

"constant, uniform, unchanging," early 15c., from Old French invariable (14c.) and directly from Medieval Latin invariabilis, from in- "not, opposite of" (see in- (1)) + variabilis "changeable" (see variable). Related: Invariably.

Related entries & more 
vector (n.)

"quantity having magnitude and direction," 1846; earlier "line joining a fixed point and a variable point," 1704, from Latin vector "one who carries or conveys, carrier" (also "one who rides"), agent noun from past-participle stem of vehere "carry, convey" (from PIE root *wegh- "to go, move, transport in a vehicle"). Related: Vectorial.

Related entries & more 
inconstant (adj.)

c. 1400, "fickle, not steadfast," from Old French inconstant "variable, eccentric" (14c.), from Latin inconstantem (nominative inconstans) "changeable, fickle, capricious," from in- "not, opposite of, without" (see in- (1)) + constantem (see constant). Related: Inconstantly.

Related entries & more 
Protean (adj.)

"of or pertaining to the Greek sea-god Proteus," 1590s, from Greek Prōteus, son of Oceanus and Tethys, who could change his form at will; hence, "readily assuming different shapes, exceedingly variable." His name is literally "first," from prōtos "first" (see proto-).

Related entries & more