Defective stop sign?

• Many-sided figure
• Nine-sider
• Odd-shaped figure
• Nine-sided polygon
• Shape with one more side than a stop sign
• Figure of horse appearing in middle of day
• A nine-sided polygon

Wikipedia Word definitions in Wikipedia
In geometry , a nonagon (or enneagon ) is a nine-sided polygon or 9-gon. The name "nonagon" is a prefix hybrid formation, from Latin ( nonus , "ninth" + gonon ), used equivalently, attested already in the 16th century in French nonogone and in English from ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"plane figure with nine sides," 1680s, a hybrid from Latin nonus "ninth" (see nones ) + ending from pentagon , etc.

Wiktionary Word definitions in Wiktionary
n. (context geometry English) A polygon with nine sides and nine angles.