Synonyms of undefended

undefended

adjective

ˌən-di-ˈfen-dəd 

as in vulnerable

lacking protection from danger or resistance against attack

the cowardly soldiers fled, leaving the palace undefended

Synonyms & Similar Words

• vulnerable
• helpless
• susceptible
• unprotected
• defenseless
• unguarded
• exposed
• unarmed
• indefensible
• unresistant
• unsafe
• in the lurch
• untenable
• passive
• weak
• overcome
• feeble
• uncovered
• abandoned
• disarmed
• preyed (on or upon)
• resistless
• high and dry
• marooned
• frail

Antonyms & Near Antonyms

• protected
• resistant
• defensible
• secure
• safe
• sheltered
• armed
• covered
• fortified
• invulnerable
• guarded
• armored
• shielded
• immune
• screened
• impregnable
• strong
• impenetrable
• invincible
• unassailable
• omnipotent
• unconquerable
• unbeatable
• almighty

Example Sentences

Recent Examples of undefended

The lack of range of Coastal Command aircraft left an undefended area known as the Mid-Atlantic Gap, rendering merchant shipping and their escorts without air cover and vulnerable to attack. — Mark Wood, TheWeek, 7 Jan. 2026

Trouba opened the scoring in the first period with an undefended slap shot after an egregious Blackhawks turnover. — CBS News, 7 Dec. 2025

Mark Collins, who was born and raised in Newfoundland, Canada, said Canadians have long treasured their friendship with the United States and the fact that the US-Canada border is the longest undefended border on the planet. — Matt Egan, CNN Money, 13 Oct. 2025

Like the global undersea cable network, the United States’ deep-water drilling infrastructure is rapidly expanding while remaining almost entirely undefended. — Robert Martinage, Foreign Affairs, 1 Jan. 2015