Consistent; unchanging from beginning to end — an idiom meaning that one's thoughts, stance, or policy are coherent throughout.
彼の説明は首尾一貫していて、信頼に足る。
His explanation is consistent from start to finish and trustworthy.
方針を首尾一貫させることが重要だ。
It's important to keep the policy consistent.
首尾一貫しない発言は混乱を招く。
Inconsistent statements cause confusion.