noun
excuse; explanation; justification; vindication
A formal or earnest verbal defense of one's actions or position; often used in contexts where someone is called to account.
彼は自分の行動について言い開きを求められた。
He was asked to give an explanation for his actions.
言い開きの
He was criticized without even being given a chance to justify himself.
Compound of 言い (continuative form of 言う 'to say') + 開き (continuative form of 開く 'to open'), literally 'opening up by saying'. The exact historical derivation is uncertain, but the meaning is conventionally associated with explaining or justifying oneself.