できる

Etymology 1
→ →  →

Originally appears in the  of 759 CE and other texts as, as a compound of. The original meaning was “to come out”, extending in figurative contexts to a sense of “to appear, to become manifest”.

Phonologically, ideku shifted to deku by the mid-1400s in the, as the low-tone initial i dropped out, vaguely similar to the way that unstressed syllables in English may disappear. This deku then underwent a common shift in Muromachi Japanese to become dekuru, where all bigrade verbs and irregular verbs underwent a shift that included a -ru on the end of the plain form, in part through a fusion of the that has always ended in -ru for these verbs, and the  that is used at the end of sentences.

As a later part of this same shift, the central vowel shifted from -u- to -i- to produce dekiru, as the main vowel -i- for the came to be used for all conjugated forms.

Over this same period, the meaning gradually shifted from “to come out” to include “to appear, to become manifest”, and from there “to come into existence anew”. This then extended further to “to occur, to happen; to be born; to be created, to be produced”, and thence “to come to fruition; to be completed, to be finished (with positive overtones)”. The underlying sense of latent existence gave rise to the meaning of “to be capable of making or producing something”, and then simply “to be able to do”.

In slang contexts in the early 1800s, dekiru came to mean “to have sex”, perhaps similar to the development of the English phrases “to do it, to get some, to get it on”.

Verb

 * 1) to be able to do
 * 2) to be finished, to be ready
 * 3) * 1949, 豊島与志雄, 或る作家の厄日:
 * 4) be made
 * 5) * 1931, 宮本百合子, なぜソヴェト同盟に失業がないか？:
 * 6)  to have sex, to do it, to get some, to get it on
 * 1) * 1931, 宮本百合子, なぜソヴェト同盟に失業がないか？:
 * 2)  to have sex, to do it, to get some, to get it on
 * 1)  to have sex, to do it, to get some, to get it on