able to be believed; convincing:

〈話･証拠などが〉信用［信頼］できる; 確実な

e.g. few people found his story credible

e.g. a credible witness.

capable of persuading people that something will happen or be successful:

〈方法･人などが〉(成功などの)見込みのある, 可能性のある(↔ incredible)

e.g. a credible threat.

late Middle English: from Latin credibilis, from credere ‘believe’.