Antonyms of verb lengthen

2 senses of lengthen

Sense 1
lengthen -- (make longer; "Lengthen this skirt, please")
       Antonym of shorten (Sense 1)
      => shorten -- (make shorter than originally intended; reduce or retrench in length or duration; "He shortened his trip due to illness")

Sense 2
lengthen -- (become long or longer; "In Spring, the days lengthen")
       Antonym of shorten (Sense 4)
      => shorten -- (become short or shorter; "In winter, the days shorten")

Synonyms/Hypernyms (Ordered by Estimated Frequency) of verb lengthen

2 senses of lengthen

Sense 1
lengthen -- (make longer; "Lengthen this skirt, please")
       => increase -- (make bigger or more; "The boss finally increased her salary"; "The university increased the number of students it admitted")

Sense 2
lengthen -- (become long or longer; "In Spring, the days lengthen")
       => grow -- (become larger, greater, or bigger; expand or gain; "The problem grew too large for me"; "Her business grew fast")