Apportion means to distribute or divide.
- The attorney wants to apportion the shares of stock evenly.
Portion, as a noun, means a limited amount of something.
- The family wants to leave a big portion of the estate to charity.
Portion, as a verb, is a synonym for apportion (distribute or divide).
- The family wants to portion part of the large estate to charity.
Proportion means a ratio of one thing to another.
- The proportion of golfers to tennis players increases every year.