Japanese edit

For pronunciation and definitions of おんせん – see the following entries.
音栓
[noun] (music) a stop or register in an organ or similar musical instrument
音線
[noun] (acoustics, physics) a sound ray, an acoustic ray
温泉
[noun] a hot spring
[noun] a spa, an onsen
(This term, おんせん, is the hiragana spelling of the above terms.)