From WordNet (r) 3.0 (2006) [wn]:
barrier
n 1: a structure or object that impedes free movement
2: any condition that makes it difficult to make progress or to
achieve an objective; "intolerance is a barrier to
understanding" [syn: barrier, roadblock]
3: anything serving to maintain separation by obstructing vision
or access
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Barrier \Bar"ri*er\, n. [OE. barrere, barere, F. barri[`e]re,
fr. barre bar. See Bar, n.]
1. (Fort.) A carpentry obstruction, stockade, or other
obstacle made in a passage in order to stop an enemy.
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2. A fortress or fortified town, on the frontier of a
country, commanding an avenue of approach.
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3. pl. A fence or railing to mark the limits of a place, or
to keep back a crowd.
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No sooner were the barriers opened, than he paced
into the lists. --Sir W.
Scott.
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4. Any obstruction; anything which hinders approach or
attack. "Constitutional barriers." --Hopkinson.
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5. Any limit or boundary; a line of separation.
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'Twixt that [instinct] and reason, what a nice
barrier! --Pope.
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Barrier gate, a heavy gate to close the opening through a
barrier.
Barrier reef, a form of coral reef which runs in the
general direction of the shore, and incloses a lagoon
channel more or less extensive.
To fight at barriers, to fight with a barrier between, as a
martial exercise. [Obs.]
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