What is the meaning of trench?

noun

• A ditch dug as a fortification having a parapet of the excavated earth.
• A long steep-sided depression in the ocean floor.
  • synonyms: deep, oceanic abyss
• Any long ditch cut in the ground.

verb

• Impinge or infringe upon.
  • usage: "This impinges on my rights as an individual"; "This matter entrenches on other domains"
  • synonyms: impinge, encroach, entrench
• Fortify by surrounding with trenches.
  • usage: "He trenched his military camp"
• Cut or carve deeply into.
  • usage: "letters trenched into the stone"
• Set, plant, or bury in a trench.
  • usage: "trench the fallen soldiers"; "trench the vegetables"
• Cut a trench in, as for drainage.
  • usage: "ditch the land to drain it"; "trench the fields"
  • synonyms: ditch
• Dig a trench or trenches.
  • usage: "The National Guardsmen were sent out to trench"