These words are used for the formal assent given to a proposed undertaking or for the official honour given upon the successful completion of a task. Approval is the most general and least formal of these. In the official context, it usually means the giving of permission to undertake a task.

• We can’t introduce our bill in the House without first getting the committee’s approval ; Would you initial this requisition as a sign of your approval ?

It can also simply mean concurrence in opinion: Your suggestion met with the principal’s highest approval .

Approbation , the most formal of these, refers to the giving of authoritative approval , especially in an ecclesiastical context. It carries overtones of warmth and congeniality in a more general context, but its use ?even in many official situations ?might be thought unnecessarily pretentious: His controversial report gained the hearty approbation of other experts in his field.

Commendation and sanction , more formal than approval , are both limited almost exclusively to an official context. Commendation is further restricted, within this context, to formal recognition for a task well done: a commendation for your brilliant sales record. The word can also refer to the written document of commendation : He framed his commendation for bravery and hung it on the wall. Sanction can mean either before-the-act approval or after-the-act commendation .

• I’m sure you can get the committee’s sanction to proceed for the way he had acted.

Caution must be observed in the use of this word for it can also mean, confusingly enough, official restrictive measures taken against a proposed act, a group of people, or a group’s behaviour: The anti-noise group said it would recommend sanctions against those factories that still offended.