A fact known from direct observation.
A premise from which conclusions are drawn.
A floating reference point, or SLDMB, used to evaluate surface currents in a body of water. Often employed by coastal search and rescue.
A fixed reference point or set of reference points which precisely define a system of measurement or a coordinate system.
To provide missing data points by using a mathematical model to extrapolate values that are outside the range of a measuring device.
Something seen; an object perceived visually.
Something unreal or imaginary; a creation of fancy.
An ideal or a goal toward which one aspires.
Pre-recorded film or tape; footage.
Something imaginary one thinks one sees.
The sense or ability of sight.
A religious or mystical experience of a supernatural appearance.
A person or thing of extraordinary beauty.
To imagine something as if it were to be true.
To present as in a vision.
To provide with a vision.