Grammar detail: verb causative form

JLPT:

verb causative form - make something happen

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The causative form of a verb means to make the verb happen.

For ichidan (る) verbs, the causative is formed by replacing the る with させる:

た

食

べる to eat ➜

た

食

べさせる make eat

For godan (う) verbs, the causative is formed by replacing the last sound (containing the う) with the equivalent あ sound, and adding せる:

う	か買う to buy ➜ か買わせる to make buy (note the use of わ)
く	き聞く to listen ➜ き聞かせる to make listen
す	はな話す to speak ➜ はな話させる to make speak
つ	ま待つ to wait ➜ ま待たせる to make wait
ぬ	し死ぬ to die ➜ し死なせる to make die
ふ	あそ遊ぶ to play ➜ あそ遊ばせる to make play
む	よ読む to read ➜ よ読ませる to make read
る	はじ始まる to begin ➜ はじ始まらせる to make begin

The causative of 'wait',

ま

待

たせる, is the root of the expression お待たせしました, which is used to mean 'sorry for keeping you waiting', but literally actually only means 'I made you wait'.

As usual する and くる are irregular, and their causatives are させる (make do) and こさせる (make come).