oc·to·thorpe 
(ŏktə-thôrp′)
(ŏktə-thôrp′)n.
The symbol (#).
[Coined in the 1960s by researchers at Bell Telephone Laboratories : OCTO- (probably in reference to the eight endpoints of the lines in the symbol) + -thorpe (perhaps from THORP, in reference to the resemblance of the symbol to a village surrounded by fields, or after James Francis Thorpe, because one of the researchers was an advocate of the restoration of Thorpe's Olympic medals).]
- on the brain
- on the breadline
- on the bubble
- on the bum
- on the button
- on the carpet
- on the cheap
- on the coattails of
- on the contrary
- on the cuff
- on the cusp
- on the defensive
- on the dole
- on the dot
- on the double
- on the drawing board
- on the edge
- on the face of it
- on the fence
- on the fly
- on the front burner
- on the go
- on the ground
- on the heels of
- on the hoof