Dictionary.net

(Math.) The Natural numbers are the series of integral numbers, beginning with unity, i.e. 1, 2, 3, etc. Natural sines, cosines, etc., of angles, are the actual sines, cosines, etc., of angles from o up to 90; they are in most cases calculated for every minute, and arranged in a tabular form; so called to distinguish them from their logarithms, which are Logarithmic sines, cosines, etc., and which are most commonly employed in astronomical and other calculations. Natural philosophy, the term used by Newton for the investigation of laws in the material world, and the deduction of results not directly observed.