"Yī tóng" literally combines "yī" (one) and "tóng" (same, together), conveying the idea of unity or shared action — essentially 'together' or 'in unison.' It functions primarily as an adverb modifying verbs, indicating that two or more people or things are doing something jointly or simultaneously. Unlike the more colloquial "yìqǐ," "yī tóng" carries a slightly formal, literary, or written register, often appearing in official notices, news reports, speeches, or polite invitations.

This phrase emphasizes coordination and collective participation rather than mere physical proximity. It’s commonly used with verbs like "cānjiā" (to participate), "qù" (to go), "jìnlì" (to strive), or "qìngzhù" (to celebrate). While it can occasionally appear as a noun meaning 'the group together,' its overwhelming usage is adverbial. Learners should avoid using it in casual spoken contexts where "yìqǐ" would sound more natural and idiomatic.