This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
詷 combines 言 (speech) with 同 (same), suggesting a meaning related to speaking in unison or agreement, but the exact historical development is uncertain.
Words 言 that are the same 同 might suggest people speaking together or agreeing, but since the meaning is unclear, picture a group all saying the same word in unison.
For トウ, imagine a group of people all saying 'toe' at the same time: toe -> トウ, and their words are the same.