Definitions of length:

• noun:   a section of something that is long and narrow

  Example: "A length of timber"

• noun:   the linear extent in space from one end to the other; the longest horizontal dimension of something that is fixed in place

  Example: "The length of the table was 5 feet"

• noun:   the property of being the extent of something from beginning to end

  Example: "The editor limited the length of my article to 500 words"

• noun:   continuance in time

  Example: "He complained about the length of time required"

• noun:   size of the gap between two places

  Example: "He determined the length of the shortest line segment joining the two points"