1. To make or keep safe from danger, attack, or harm.
2. Sports
   1. To attempt to prevent the opposition from scoring while playing in or near (a goal or area of a field, for example).
   2. To be responsible for guarding (an opposing player).
   3. To compete against a challenger in an attempt to retain (a championship).
   4. To represent (a defendant) in a civil or criminal action.
   5. To attempt to disprove or invalidate (an action or claim).
3. To support or maintain, as by argument or action; justify.
4. Law
   1. To represent (a defendant) in a civil or criminal action.
   2. To attempt to disprove or invalidate (an action or claim).

1. To make a defense.
2. Sports To play defense.

Synonyms: These verbs mean to make or keep safe from danger, attack, or harm. Defend implies repelling an attack: defending her territory; defended his reputation.
Protect often suggests providing a barrier to discomfort, injury, or attack: bought a dog to protect the children; wore sunglasses to protect her eyes.
Guard suggests keeping watch: guarded the house against intruders.
To preserve is to take measures to maintain something in safety: ecologists working to preserve our natural resources.
Shield suggests protecting with a piece of defensive armor: hid the newspaper to shield me from the bad news.
Safeguard stresses protection against potential danger: The Bill of Rights safeguards our individual liberties.