A number representing the increment between two figurate numbers (“numbers equal to the numbers of dots in geometric figures formed of dots”).
A plane figure formed by removing a parallelogram from a corner of a larger parallelogram.
An object such as a pillar or a rod that is used to tell time by the shadow it casts when the sun shines on it, especially the pointer on a sundial.
An object such as a pillar used by an observer to calculate the meridian altitude of the sun (that is, the altitude of the sun when it reaches the observer's meridian), for the purpose of determining the observer's latitude.
The index of the hour circle of a globe.
A family of geometric objects with a common property, such as the set of lines that pass through a given point in a projective plane.
A paintbrush.
A writing utensil with a graphite (commonly referred to as lead) shaft, usually blended with clay, clad in wood, and sharpened to a taper.
An aggregate or collection of rays of light, especially when diverging from, or converging to, a point.
To write (something) using a pencil.
To mark with, or as if with, a pencil.