Definition: a Cross-functional Team is a group of people whose members hold different backgrounds, expertise and functions working toward shared objectives. A CFT is also known as a multidisciplinary team or an interdisciplinary team.
For example, a CFT can be constituted by people from Sales, Marketing, Finance, Engineering, Procurement, Design, Customer Services, etc...
The team composition of a CFT is heterogenous.
A CFT is the opposite of a functional team.
Note that team members can also differ on many other dimensions (besides their discipline or function), such as age, gender, ethnicity, religion, culture, personality, beliefs and attitudes.