noun
worth mentioning; worth saying
Used to express that something is worth the effort of saying, often in the phrase 言い甲斐がある.
彼の話にはいつも言い甲斐がある。
His stories are always worth telling.
こんなに反響があるなら、言い甲斐があった。
With this much response, it was worth saying.
やり甲斐 means 'worth doing' or 'rewarding', while 言い甲斐 specifically refers to the worth of saying something.
Compound of 言い (the continuative form of 言う 'to say') and 甲斐 'worth, effect'. The exact historical derivation is uncertain, but the word follows the common pattern of attaching 甲斐 to a verb stem to express 'worth doing'.