when the feeling of motivation or enthusiasm for something is strong enough that a person is fully prepared to spend a considerable portion of his or her available assets (i.e. money, time) on it
All Jack is interested in is getting laid. So much of his spending money goes towards taking women out for dinner and drinks.
Dennis was so interested in climate change that he liquidated his 401k to spend three months doing research in the Arctic.
A male/female who is more than curious about experimenting with the same sex. The person has had some intimate contact with the same sex, but is not openly bi-sexual. Bi-interested is the middle ground between bi-curious and bi-sexual.