the GNU version of the Collaborative International Dictionary of English
n. The art or science of dialing, or of constructing dials to show the hour of the day by the shadow of a gnomon.
The Century Dictionary and Cyclopedia
n. The art or science of dialing, or of constructing instruments to show the hour of the day or to aid in making astronomical observations by the shadow of a gnomon.
Word Usage
"Before clocks were invented, people told the time by sun-dials, and there was a whole science of sun-dials, called gnomonics."