natural in Wingdings is ■︎♋︎⧫︎◆︎❒︎♋︎●︎

Belonging to, to be taken in, or referred to, some system, inwhich the base is 1; -- said or certain functions or numbers; as,natural numbers, those commencing at 1; natural sines, cosines, etc.,those taken in arcs whose radii are 1.