a. A linear array of digits that contains a single period, called the decimal point, is possibly preceded by a minus sign (-), and represents a real number, with each successive digit to the right of the decimal point indicating a multiple of the next negative power of 10, and each successive digit to the left of the decimal point indicating a multiple of the next non-negative power of ten, beginning with 100 = 1. For example, 245.3 represents the real number (2 × 102) + (4 × 101) + (5 × 100) + (3 × 10-1) = 200 + 40 + 5 + 3/10 , and -1.04 represents the real number (-1 × 100) + (-4 × 10-2). Also called mixed decimal.
b. Such an array of digits in which there are no nonzero digits to the left of the decimal point, representing a real number between -1 and 1. Also called decimal fraction.
2. A number written using the base 10.
1. Expressed or expressible as a decimal.
a. Based on 10.
b. Numbered or ordered by groups of 10.
[Medieval Latin decimālis, of tenths or tithes, from Latin decima, a tenth part or tithe, from decem, ten; see dek in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.