Gikun
I recently learned of the existence of gikun (義訓) words in the Japanese language. Basically, these are words that only have a semantic connection with the characters used to write them. As an example, the Japanese word for jellyfish can be written with as 海月 (sea + moon) or 水母 (water+mother) - but neither variant utilizes the characters' usual readings.
Has any research been done regarding this category of words? It seems strange to me that these words should have kanji assigned to them that have no phonetic connection. The only reason I can think of is that the Chinese writing system lacked the characters needed to express noun concepts such as jellyfish or starfish (another gikun word), but the original words were too widely used to make up and adopt new ones based on the on readings of the characters.
Has any research been done regarding this category of words? It seems strange to me that these words should have kanji assigned to them that have no phonetic connection. The only reason I can think of is that the Chinese writing system lacked the characters needed to express noun concepts such as jellyfish or starfish (another gikun word), but the original words were too widely used to make up and adopt new ones based on the on readings of the characters.