deci-

Proto-Indo-European root meaning "ten."

It forms all or part of: cent; centenarian; centenary; centi-; centime; centurion; century; centennial; cinquecento; dean; deca-; decade; decagon; Decalogue; Decameron; decapod; decathlon; December; decennial; deci-; decile; decimal; decimate; decimation; decuple; decussate; denarius; denier (n.) "French coin;" dicker; dime; dinar; doyen; dozen; duodecimal; duodecimo; eighteen; fifteen; fourteen; hecatomb; hendeca-; hundred; icosahedron; nineteen; nonagenarian; octogenarian; Pentecost; percent; quattrocento; Septuagint; sexagenarian; seventeen; sixteen; ten; tenth; thirteen; thousand; tithe.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit dasa, Avestan dasa, Armenian tasn, Greek deka, Latin decem (source of Spanish diez, French dix), Old Church Slavonic deseti, Lithuanian dešimt, Old Irish deich, Breton dek, Welsh deg, Albanian djetu, Old English ten, Old High German zehan, Gothic taihun "ten."

1928, from deci- + bel (n.).

Progress in science and industry is constantly demanding new terms and one of the latest of these is the word "decibel," coined by telephone engineers to describe the efficiency of telephone circuits. It is a substitute for the phrase "transmission unit." The actual unit decided upon was first called "bel," after the inventor of the telephone. The bel, however, is larger than is needed in practice, and, therefore, a unit one-tenth as large was adopted by engineers and named the decibel. [Popular Mechanics, May 1929]

"measure of length equal to the tenth part of a meter, 1809, from deci- + meter (n.2).