something that is certain

positive assurance

the addition of a particular word or words, the spoken force used etc to make the significance clear or to show importance when speaking or writing

importance, prominence

a feeling of confidence, strong belief, (in the goodness, strength, reliability of a person or thing); (an arrangement for) money or property held and managed by one or more people (trustees) for the benefit of another or others

belief in something as true, trustworthy