› to share something between several people or organizations: apportion sth between sb/sth The costs will be apportioned between the buyer and the seller.apportion sth to sb/sth She apportioned 25% of her estate to her grandchildren.apportion sth among sb/sth International agreements apportioning flights among airlines will soon be a thing of the past.
› INSURANCE, LAW to decide who is responsible for an accident or event, especially when deciding how much of the costs each person, insurance company, etc. should pay: I'm not here to apportion blame, but only to try and resolve the problem. Liability was apportioned 80-20 in his favour.
› ACCOUNTING, TAX to divide costs between different accounts or uses: apportion sth between sb/sth Items such as gas and electricity bills can be apportioned between home and work use.