The overside or up-side of a flat object such as a table, or of a liquid. / The outside hull of a tangible object. / (figuratively) Outward or external appearance.

(transitive) To provide something with a surface. / (transitive) To apply a surface to something. / (intransitive) To rise to the surface. / (transitive) To bring to the surface.

Something unexpected. / The feeling that something unexpected has happened.

(transitive) To cause (someone) to feel unusually alarmed or delighted by something unexpected. / (transitive) To do something to (a person) that they are not expecting, as a surprise.

(informal) An elderly person who regularly uses the Internet.

A substitute (usually of a person, position or role). / A person or animal that acts as a substitute for the social or pastoral role of another, such as a surrogate parent.

Of, concerning, relating to or acting as a substitute.

(transitive) To replace or substitute something with something else; to appoint a successor.

Physically secure and certain, non-failing, reliable. / Certain in one's knowledge or belief. / (followed by a to infinitive) Certain to act or be a specified way.

(modal adverb) Without doubt, certainly. / (archaic) Without fail, surely.