とも

1. 1Even if a hypothetical condition holds, the main-clause result or decision does not change.Ex. 1
2. 2With a question word: no matter who, what or how, the speaker's stance stays unchanged.Ex. 2

A formal, somewhat literary concessive used in writing, speeches and firm declarations of resolve. The main clause usually expresses determination, a decision or an unchanging fact. It sounds weightier and stiffer than everyday ても, which carries the same basic concessive meaning.

• てもN4「ても」 has the same meaning as 「とも」 and can likewise combine with question words to mean 'no matter...'. The difference lies in conjugation and register: 「ても」 attaches to the te-form (降っても) and is used in both speech and writing, while 「とも」 attaches to the volitional form and tends to sound formal and stiff, so 「ても」 is the better choice in conversation.
• といえどもN1「といえども」 attaches directly to nouns or the plain form and often emphasizes that even a person's status or position—or the smallest amount—is no exception, whereas 「とも」 usually attaches to the volitional form or to forms like 「かろう」 and 「であろう」. When paired with words such as 「どんなに」, the two are close in meaning, and both lean toward written style.
• にしろ / にせよN2「にしろ」/「にせよ」 also express concession, but they attach directly to nouns and the plain form and can be paired as 「AにしろBにしろ」. They generally do not describe facts that have already happened, whereas 「とも」 can, and 「にしろ」 is also common in speech.
• にしてもN2「にしても」 attaches to the plain form or a noun and is neutral in register; the first clause is usually a known fact, the second often carries an evaluation or dissatisfaction, and there is also the paired usage 「AにしてもBにしても」. 「とも」 attaches to the volitional form and the like, and is more formal and resolute.
• たってN3「たって」 is essentially identical in meaning to 「とも」 (including its use with question words), but it is colloquial and often emotional, attaching to the ta-form (降ったって). Use 「とも」 in formal written contexts and 「たって」 in everyday conversation.
• であれ / であろうとN1「であれ」/「であろうと」 attach only to nouns, question words, and na-adjectives—they cannot attach to verbs. With nouns they mean the same as 「であろうとも」 and are interchangeable, as in 「誰であれ」 and 「どんな困難であろうと」; both lean toward written style.

ても and the very casual たって express the same concession in neutral or colloquial speech, while にしても and にしろ / にせよ are less literary and are also often used to set out alternatives (whether A or B). といえども ("even though it is X") and であれ / であろうと are formal like とも but mainly follow nouns, whereas とも typically follows verb volitional forms.