Qualia
Etymology
The Latin "qualia" is the plural of "quale" (of what kind, from "qualis"). The American philosopher C.I. Lewis gave it its modern technical sense in 1929, and it now names the ineffable qualitative properties of conscious experience.
noun · /KWAH-lee-uh/
The raw, subjective feel of an experience — the redness of red or the ache of a headache — as it seems from the inside.
What it names
A handle for the felt, first-person character of consciousness that seems to escape any physical description — reach for it when arguing whether science can fully explain the mind.
Example
A color-blind scientist could know every fact about wavelengths and still lack the qualia of actually seeing red.
Related idea
Contrast with intentionality, the mind’s “aboutness”; qualia concern how experience feels, whereas intentionality concerns what a thought is directed at.