The purpose of this study was to research for the etymology of Korean words in terms of ideation. The etymology of Korean words has never been properly studied till today, due to the scarce historical materials and the insufficient researches. This study has been executed with a main focus on the etymology of middle term, rather than the original etymology. Ideation is made mainly through 5 organs of sense. Naming and word-formation in the vocabulary of Korean language, especially the substantive of original Korean, are made most frequently by the ideation through the sense of sight; and less frequently through the auditory sense; but very rare through the other sense. For ideation and naming through the sense of sight, predominating is the sense of shape, over the others such as the color sense and the optic sense. Naming through the sense of shape may have 2 different categories such as shape and condition; or 10 different ones such as distinctive characteristic, place of residence, direction, material, habit, usage, growth, season and sex. For sense other than sight, this study found some onomatopoeias and their derivatives, both through auditory sense; some adjectives, developed through the sense of taste; and few complex words are typically found using “~nae(~내) as like a suffix. For the sense of touch, the main stream is adjectives, through the sense of pressure.