unfailing

adjective

1. not liable to failure

- the unfailing sign of an amateur

- an unfailing test

Similar word(s): infallible, foolproof

2. always able to supply more

- an unfailing source of good stories

- a subject of unfailing interest

Similar word(s): inexhaustible

3. unceasing

- unfailing loyalty

- unfailing good spirits

Similar word(s): constant, unflagging