Decimal (?), a. [F. décimal (cf. LL. decimalis), fr. L. decimus tenth, fr. decem ten. See Ten, and cf. Dime.] Of or pertaining to decimals; numbered or proceeding by tens; having a tenfold increase or decrease, each unit being ten times the unit next smaller; as, decimal notation; a decimal coinage.
[1913 Webster]

Decimal arithmetic, the common arithmetic, in which numeration proceeds by tens. -- Decimal fraction, a fraction in which the denominator is some power of 10, as 2/10, 25/100, and is usually not expressed, but is signified by a point placed at the left hand of the numerator, as .2, .25. -- Decimal point, a dot or full stop at the left of a decimal fraction. The figures at the left of the point represent units or whole numbers, as 1.05.
[1913 Webster]