lengthening

(noun) the act of prolonging something. Synonyms: prolongation, protraction, perpetuation. Example: "There was an indefinite prolongation of the peace talks."

(verb) make longer. Synonyms: lengthen. Example: "Lengthen this skirt, please."

(verb) become long or longer. Synonyms: lengthen. Example: "In spring, the days lengthen."