A loud shout raised by a group before or during battle to boost morale or intimidate the enemy. Most commonly encountered in the set phrase 鬨の声 (ときのこえ). It is also written as 時, though this is rare.
See also: 鬨の声
戦の前に、兵士たちは鬨の声を上げた。
Before the battle, the soldiers raised a war cry.
時代劇で「えいえいおう」という鬨の声を聞いたこと
I've heard the battle cry 'Ei ei ou!' in period dramas.
掛け声 is a general 'shout' or 'call' used to synchronize effort or encourage someone, not limited to battle contexts.
Standard kanji for 'battle cry'. The reading とき is not obvious from the character, so learners may need to memorize it.
Rarely used kanji form. Literally 'whale wave', but used here as ateji for the sound of a war cry.
The origin is uncertain. The kanji 鬨 is composed of 門 (gate) and 共 (together), suggesting a cry raised together at the gate, but this is likely a mnemonic rather than a historical derivation. The reading とき may be related to 時 (time) as in a signal to begin, but this is speculative.