: going straight up or to the side at a 90 degree angle from another line or surface
What made you want to look up perpendicular? Please tell us where you read or heard it (including the quote, if possible).
Take Our 10-Question Quiz
The commonly misspelled words quiz
How strong is your vocabulary?
The Vocab Quiz Game for iPhone & iPad
"Incredibly fun and addictive. And informative!" User Review, iTunes