Defective stop sign?

• Nine-sider
• A regular one has internal angles of 140 degrees
• Odd-shaped figure
• Nine sided object
• Shape of a Bahai temple
• Shape with one more side than a stop sign
• Canon agonises somewhat to reveal figure

WordNet Word definitions in WordNet
n. a nine-sided polygon

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

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.