Teleological

Serving an ultimate purpose in its design.

For example, 'What is the true purpose of the nose?' That is a teleological question.

For another example, to say that all evolutionary changes occur for a definite purpose is a teleological explanation of evolution.

'Teleological' comes from ancient Greek roots but did not enter English until the 18th century.

It is a compound of the Greek 'tele-, telos,' meaning 'end or purpose' + the ending 'logos' meaning 'the science or study of' = the study of the ends or purposes.