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.
An individual observer's own subjective perception of that which is real.
The entirety of all that is real.
The real world.
The state of being actual or real; realness.
A real entity, event, or other fact.