indolence n.

word-forming element meaning "not, opposite of, without" (also im-, il-, ir- by assimilation of -n- with following consonant, a tendency which began in later Latin), from Latin in- "not," cognate with Greek an-, Old English un-, all from PIE root *ne- "not."

In Old French and Middle English often en-, but most of these forms have not survived in Modern English, and the few that do (enemy, for instance) no longer are felt as negative. The rule of thumb in English has been to use in- with obviously Latin elements, un- with native or nativized ones.

late 13c., with -ful, from Middle English dole "emotion of grief, sorrow, lamentation, mourning" (early 13c., now archaic), from Old French doel (Modern French deuil), from Late Latin dolus "grief," from Latin dolere "suffer, grieve," which is of uncertain origin. De Vaan explains it as from PIE *dolh-eie- "to split" (source also of Middle Welsh e-thyl "chooses"), a causative verb from root *delh- "to chop," "under the assumption than 'pain' was expressed by the feeling of 'being torn apart'." Related: Dolefully; dolefulness.

1660s, "causing no pain, painless," from French indolent (16c.) or directly from Late Latin indolentem (see indolence). Sense of "living easily, slothful," is 1710, a sense perhaps developed in French. Related: Indolently.