a straight line on which there is indicated a one-to-one correspondence between points on the line and the set of real numbers.
Origin of number line
First recorded in 1955–60
Also called real line.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
an infinite line on which points represent the real numbers
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012