félnyílt

Félnyílt is a Hungarian adjective meaning partially opened, not fully opened or closed. It is used to describe objects whose aperture lies between fully closed and fully open, such as a door left ajar, a window that is slightly opened, or a lid that is not fully raised. In figurative use, it can describe a state that is not fully settled or decided.

Etymology and usage: The word is formed from fél (half) and nyílt (opened). It is commonly written as félnyílt and used in both everyday language and technical contexts. In everyday speech a félnyílt ajtó or ablak conveys a small gap. The term emphasizes partial openness rather than complete status.

In mathematics and related fields: The term is also used to describe half-open intervals. A félnyílt intervallum [a, b) is closed on the left and open on the right; equivalently (a, b] is open on the left and closed on the right. These sets appear frequently in real analysis and topology and are contrasted with open intervals (a, b) and closed intervals [a, b].

See also: open interval, half-open interval.