Definitions of shorten:

• verb:   become short or shorter

  Example: "In winter, the days shorten"

• verb:   make shorter than originally intended; reduce or retrench in length or duration

  Example: "He shortened his trip due to illness"

• verb:   make short or shorter

  Example: "Shorten the skirt"

• verb:   reduce in scope while retaining essential elements

  Example: "The manuscript must be shortened"

• verb:   edit by omitting or modifying parts considered indelicate
• name:  A surname (very rare: popularity rank in the U.S.: #54245)