も同然だ【もどうぜんだ】

The expression も同然だ (もどうぜんだ) means "is practically the same as," "is as good as," or "is virtually the same as." It is used to emphasize that something is so close to a certain state or condition that it can be considered equivalent to it, even if it is not literally so.

どうぜん同然 means "equivalent" or "the same as," and the particle も adds the nuance of "even" or "indeed," reinforcing that the comparison is apt.

Usage with nouns

When attached to a noun, も同然だ states that something is practically the same as that noun.

Usage with verb た-form

When attached to a verb in the past tense (た-form), も同然だ expresses that an action is as good as done – it is so close to completion or so inevitable that it can be treated as already accomplished.

Usage with ない form

Combined with the negative form of a verb, も同然だ conveys that something effectively did not happen or does not exist.

Nuance

This is a fairly formal and emphatic expression, commonly found in written Japanese, news commentary, and deliberate speech. It carries a strong evaluative tone – the speaker is making a judgment that two things are equivalent. It differs from みたいだ or ようだ in that those express resemblance or appearance, while も同然だ asserts near-total equivalence.