Shogakukan Unabridged Dictionary of the Japanese Language (2nd Edition)

Notes

Etymology Section

Etymological derivations found in various sources are summarized in the Etymology (【語源説】;gogensetsu) Section, accompanied by the title of source provided in brackets 〔　〕.
When two or more origins are given for a single word, they are given following numbered parentheses (1), (2), etc. In many cases the order of presentation is based on conceptual similarity rather than historical order or reliability.
When several sources give similar etymologies for an item, such etymologies are summed up into a common denominator, with the source titles placed in parentheses　〔　〕 roughly in chronological order.

Etymological summaries are presented in such a way as to retain the original contentions of the source texts as much as possible, but the following procedures are followed:

a)	In referring to the origin of a word and in describing its sound changes, the word is rendered in katakana, with the corresponding kanji given in parentheses ( 　). However, the original kana orthography is respected.
b)	Etymologies based on oral tradition, conjecture, etc. are indicated by expressions such as ‘to iu’ (という; so legend goes) and ‘ka’ (か; presumably so).

Source titles are provided as fully as possible. For modern sources, authors’ names are given after the title, preceded by the symbol “=.”