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.
A knowable thing or event (eg by inference, especially in science)
An experienced object whose constitution reflects the order and conceptual structure imposed upon it by the human mind (especially by the powers of perception and understanding).
A thing or being, event or process, perceptible through senses; or a fact or occurrence thereof.
A kind or type of phenomenon (sense 1 or 2)
A fact or event considered very unusual, curious, or astonishing by those who witness it.
A wonderful or very remarkable person or thing.
Appearance; a perceptible aspect of something that is mutable.