English word decagon comes from English -gon, English deca-
| Dictionary entry | Language | Definition |
|---|---|---|
| -gon | English (eng) | (geometry) Forms the names of plane figures containing a given number of angles, and thus bounded by that number of line segments (polygons). If the number is large enough, it can be attached directly to an English numeral with a hyphen. |
| deca- | English (eng) | In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10. Symbol: da. Ten. |
| decagon | English (eng) | (geometry) A polygon with ten sides and ten angles. |