Definitions of trench:

• noun:   a ditch dug as a fortification having a parapet of the excavated earth
• noun:   any long ditch cut in the ground
• noun:   a long steep-sided depression in the ocean floor
• verb:   dig a trench or trenches

  Example: "The National Guardsmen were sent out to trench"

• verb:   cut a trench in, as for drainage

  Example: "Trench the fields"

• verb:   set, plant, or bury in a trench

  Example: "Trench the fallen soldiers"

• verb:   cut or carve deeply into

  Example: "Letters trenched into the stone"

• verb:   fortify by surrounding with trenches

  Example: "He trenched his military camp"

• verb:   impinge or infringe upon

  Example: "This matter entrenches on other domains"

• name:  A surname (very rare: popularity rank in the U.S.: #41816)