- A structure built for defense surrounding a city, castle etc.
"The town wall was surrounded by a moat."
- (chiefly dialectal) A spring of water.
- A point of defeat or extinction.
- (often in combination) A barrier.
"a seawall; a firewall"
- (anatomy, zoology, botany) A divisive or containing structure in an organ or cavity.
- (Internet) A personal notice board listing messages of interest to a particular user.
- A rampart of earth, stones etc. built up for defensive purposes.
- A point of desperation.
- A type of butterfly (Lasiommata megera).
- Something with the apparent solidity and dimensions of a building wall.
"a wall of sound; a wall of water"
- (soccer) A line of defenders set up between an opposing free-kick taker and the goal.
- Each of the substantial structures acting either as the exterior of or divisions within a structure.
"We're adding another wall in this room during the remodeling. The wind blew against the walls of the tent."
- (nautical) A kind of knot often used at the end of a rope; a wall knot or wale.
- An impediment to free movement.
"A wall of police officers met the protesters before they reached the capitol steps."
- A barrier to vision.
- (auction) A fictional bidder used to increase the price at an auction. Also called a chandelier.
- To enclose with a wall
"He walled the study with books."
- (with "up") To seal with a wall
"They walled up the basement space that had been used as a coal bin."
- (with "off") To separate with a wall
"The previous owners had walled off two rooms, making an apartment."
- To well, as water; spring.
- (with "in") To enclose by surrounding with walls.
"They had walled in the garden"
- To boil.