Word Study
on account of |
on air |
on all fours |
on an individual basis |
on an irregular basis |
on and off
| on and on
| on approval
| on average
| on base
| on board
on and off
WORDNET DICTIONARY
Adverbial on and off has 1 sense
- on and off(r = adv.all) off and on - not regularly; "they phone each other off and on"
For further exploring for "on and off" in Webster Dictionary Online
(NT only) to listen to the NET Bible 
