Why is 対馬 pronounced つしま?


The island of Tsushima is written 対馬{つしま}. Why? No reading of 対 and 馬 can
produce つしま, and clearly つしま has something to do with 島{しま}. There seems to
also be no gikun-type motivation in meaning to write 対馬, which honestly is a
weird name for an island ("against a horse"?).

The Korean and Chinese names do use the characters 対馬 and Chinese-based
readings though ( _daema_ and _duima_ ). However, it seems unlikely that the
Chinese/Korean name came first, as the island is Japanese throughout history.
In any case, even if 対馬 came from Chinese, why keep the つしま name?




According to the Japanese wikipedia page, in 古事記{こじき}, it is recorded as 津島 -
this fits the reading and may indicate the original meaning of the name. The
slightly later 日本書紀{にほんしょき} records「対馬洲」and「対馬島」.

So we probably have つしま as the original name, pre-dating kanji, a possible way
of writing it in kanji, 津島, and another, 対馬 adopted from the Chinese/Korean.
The fact that 対馬 eventually won out is just an accident of history - it
probably suggests that 津島 was not an established way of writing the name.

Regarding the origin of 対馬, 対 can also mean "a couple/pair".
[This](http://www.tisen.jp/tisenwiki/?%C2%D0%C7%CF) interesting discussion of
the origins suggests it may have previously been 対島 - referring to the shape
(even before it was split in two in 1671 it could have been taken as two
halves), or related to an old placename on the Korean peninsula - 馬韓 - making
it "the island facing 馬(韓)".

There are, apparently, no horses on the island.




According to the Japanese wikipedia page, in 古事記{こじき}, it is recorded as 津島 -
this fits the reading and may indicate the original meaning of the name. The
slightly later 日本書紀{にほんしょき} records「対馬洲」and「対馬島」.

So we probably have つしま as the original name, pre-dating kanji, a possible way
of writing it in kanji, 津島, and another, 対馬 adopted from the Chinese/Korean.
The fact that 対馬 eventually won out is just an accident of history - it
probably suggests that 津島 was not an established way of writing the name.

Regarding the origin of 対馬, 対 can also mean "a couple/pair".
[This](http://www.tisen.jp/tisenwiki/?%C2%D0%C7%CF) interesting discussion of
the origins suggests it may have previously been 対島 - referring to the shape
(even before it was split in two in 1671 it could have been taken as two
halves), or related to an old placename on the Korean peninsula - 馬韓 - making
it "the island facing 馬(韓)".

There are, apparently, no horses on the island.

