Note: If you do this sign "larger" it can mean "board" as in white board or blackboard.
“SQUARE-perimeter” can be used to indicate a billboard or display
sign. This is a very "general" sign used to indicate whatever
is "square shaped."
Add black to it and you have: BLACK + BOARD
Add White to it and you have: WHITE + BOARD
square / board / sign
Blackboard
American Sign Language University ™ ASL resources by Lifeprint.com © Dr. William Vicars