
Word families (Nouns, Verbs, Adjectives, Adverbs): fail, failure, fail, unfailing, unfailingly
Xem thêm: foolproof, unflagging
adj.
a foolproof identification system
the unfailing sign of an amateur
an unfailing test
an unfailing source of good stories
a subject of unfailing interest
unfailing loyalty
unfailing good spirits
unflagging courtesy