1. the process or result of making something longer

1. present participle of lengthen; making or becoming longer

Examples

• The lengthening of the school day was controversial among parents.
• She noticed a gradual lengthening of the shadows as evening approached.
• The tailor is lengthening the dress for the tall customer.
• Days are lengthening as spring approaches.
• The lengthening of the bridge took six months to complete.
• He was lengthening his stride to keep up with the group.
• The lengthening process requires careful measurement.