It always intrigued me how some readings came to linguistically and historically. One I've been wondering about is 躑る (たちもとおる). Can't seem to find anything about this specific reading. But how would I even approach something like this in general? I've had this multiple times already and I'm really interested in the history and change these words underwent. (Another example would be 概 とかき)
1 Answer
Verbs longer than maybe 4 morae (for Conclusive form) are practically guaranteed to be compounds. Single kanji happened to have been assigned for some compounds.
Examples:
試{こころ}みる is compound of 心{こころ} + 見{み}る.
承{うけたまわ}る is compound of 受{う}け (Continuative form of 受ける) + 賜{たまわ}る.
翻{ひるがえ}る is compound of something + 返{かえ}る (with rendaku). See speculation in this answer.
覆{くつがえ}る is compound of something + 返{かえ}る (with rendaku). See speculation in this answer.
退{しりぞ}く is compound of 尻{しり}・後{しり} + 退{そ}く (with rendaku). Note the same kanji for spelling both verbs.
躑{たちもとお}る seems to be compound of 立{た}ち (Continuative of 立{た}つ) + もとおる.
もとおる is modernized spelling of もとほる ("to wander around"), which maybe had kanji spellings 回る, 廻る, and had transitive equivalent もとほす. See also description of もとほる here and description of もとほす here. (Description of pre-1946 orthography here.)
Actual pronunciation of もとほる was:
[motoporu] → [motoworu] → [motooru] ~ [motoːru]
(So you should not try to pronounce it as [motohoru].)