noun

1. Something or someone reliable or dependable

   “the old reliables”

adjective

1. Suitable or fit to be relied on; worthy of dependence, reliance or trust; dependable, trustworthy

2. (of a communication protocol) Such that either a sent packet will reach its destination, even if it requires retransmission, or the sender will be told that it didn't

Synonyms: dependable, secure, trustworthy, trusty