Dictionary.net

• Having three quadrants; thus, a triquadrantal triangle is one whose three sides are quadrants, and whose three angles are consequently right angles.

2010 - New Age Dictionary Database
By Oddity Software

• Having three quadrants; thus, a triquadrantal triangle is one whose three sides are quadrants, and whose three angles are consequently right angles.

1913 - Webster's Revised Unabridged Dictionary
By Noah Webster.