If you do something on someone's behalf, you do it for that person as their representative. The form in someone's behalf is also used, mainly in American English. She made an emotional public appeal on her son's behalf Secret Service officer Robin Thompson spoke on behalf of his colleagues
for someone's benefit (usually expressed as `in behalf' rather than `on behalf' and usually with a possessive); "in your behalf"; "campaigning in his own behalf"; "spoke a good word in his friend's behalf"
If you feel, for example, embarrassed or angry on someone's behalf, you feel embarrassed or angry for them. `What do you mean?' I asked, offended on Liddie's behalf. on behalf of sb in behalf of sb a) instead of someone, or as their representative (by half )
as the agent of or on someone's part (usually expressed as "on behalf of" rather than "in behalf of"); "the guardian signed the contract on behalf of the minor child"; "this letter is written on behalf of my client"
rather than "in behalf of"); "the guardian signed the contract on behalf of the minor child"; "this letter is written on behalf of my client"; for someone's benefit (usually expressed as `in behalf' rather than `on behalf' and usually with a possessive); "in your behalf"; "campaigning in his own behalf"; "spoke a good word in his friend's behalf"