Antonyms for the phrase "stands one's ground" would involve words that express the opposite action. These words would imply that someone is retreating, backing down or giving in. Some possible antonyms for "standing one's ground" might include: surrendering, caving in, yielding, submitting, capitulating, backing away, withdrawing, fleeing or escaping. All of these words suggest some form of defeat or resignation rather than standing up for oneself. It's important to remember that there are times when it may be wise to back away from a confrontation or to seek a compromise, but other times, standing one's ground can be an important act of courage and strength.
