due

Concise Oxford English Dictionary © 2008 Oxford University Press:
due/djuː/

▶adjective

• 1 expected at, planned for, or required by a certain time.

  ■ (of a person) owed or deserving (something).

  ■ required as a legal or moral obligation.

• 2 proper; appropriate.

▶noun

• 1 (one's due/dues) one's right.

• 2 (dues) fees.

▶adverb (with reference to a point of the compass) directly: head due south.

– phrases
due to

• 1 caused by.

• 2 because of.

give someone their due be fair to someone.
in due course at the appropriate time.
pay one's dues fulfil one's obligations.

– origin ME: from OFr. deu ‘owed’, based on L. debitus ‘owed’, from debere ‘owe’.

usage: Some people regard due to in the sense ‘because of’ as incorrect on the grounds that due is an adjective and should not be used in a prepositional phrase; owing to is often recommended as a better alternative. However, this use of due to is now very common in all types of literature and is regarded as part of standard English.