Not to be doubted or denied; established as a fact.
Unfailing; infallible.
Known but not specifically named; indeterminate; indefinite; one or some; sometimes used independently as a noun, and meaning certain persons; see also "one".
Fixed or stated; regular; determinate.
Sure, positive, not doubting.
Actually existing; sure to happen; inevitable.
Having been determined but not specified.
Unnamed or undescribed members (of).
Suitable or fit to be relied on; worthy of dependence, reliance or trust; dependable, trustworthy
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
Something or someone reliable or dependable