High vacuum thread sealant. b. I looked down from the high window. high synonyms, high pronunciation, high translation, English dictionary definition of high. High is a general term, and denotes either extension upward or position at a considerable height: six feet high; a high shelf. The bridge was high, jacked up on wooden piers. If something is high, it is a long way above the ground, above sea level, or above a person or thing. high implies marked extension upward and is applied chiefly to things which rise from a base or foundation or are placed at a conspicuous height above a lower level. a. Derived forms: highs, highest, higher. Aug 28, 2012 · Pertaining to (or, especially of a language: spoken in) in an area which is at a greater elevation, for example more mountainous, than other regions.