in or on behalf of, as a representative of or a proxy for: On behalf of my colleagues, I address you tonight.
2.
in or on (someone's) behalf, in the interest or aid of (someone): He interceded in my behalf.
Origin: 1400–50; late ME; ME bihalve, earlier as adv. and prep. with the sense “near(by),” orig. as prep. phrase bi halve on one side; see be-, by, half
[bi-haf, -hahf] 
