There are 12 words that start with 'behavi'.
| behaving | behavior | 
| behaviors | behaviour | 
| behavioral | behaviours | 
| behaviorism | behaviorist | 
| behaviorally | behaviorisms | 
| behaviorists | behavioristic | 
Note: These 12 words that start with 'behavi' are found from the USA & Canada version of the tournament Scrabble word list.