Pronunciation: (u-prOO'vul),[key] —n. 1. the act of approving; approbation.
2. formal permission or sanction.
3. Philately.one of a group of selected stamps sent by a dealer to a prospective customer for examination and either purchase or return.
4. on approval, without obligation to buy unless satisfactory to the customer upon trial or examination and, otherwise, returnable: We ship merchandise on approval.