intangible (adj.)

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.

1580s, "capable of being touched," from French tangible and directly from Late Latin tangibilis "that may be touched," from Latin tangere "to touch," from PIE root *tag- "to touch, handle." Sense of "material" (as in tangible reward) is first recorded 1610s; that of "able to be realized or dealt with" is from 1709. Related: Tangibly.