yodan verb with 'tsu' ending (archaic), intransitive verb
talk to oneself; mutter to oneself
Archaic yodan verb; in modern Japanese the related form 独りごちる is more common. Used in classical or poetic contexts.
See also: 独りごちる
老人は縁側でひとりごちていた。
The old man was muttering to himself on the veranda.
古典
In classical texts, 独り言つ is sometimes read as ひとりごつ.
Modern equivalent; 独りごちる is the current standard verb for 'to talk to oneself', while 独り言つ is its archaic predecessor.
Compound of 独り (ひとり, 'alone') + 言つ (ごつ, archaic verb 'to say'). The verb ごつ is an old form related to 言う (いう).