Barricade, n.
Etymology: [F. barricade, fr. Sp. barricada, orig. a barring up with casks; fr. barrica cask, perh. fr. LL. barra bar. See Bar, n., and cf. Barrel, n.]
1. (Mil.)
A fortification, made in haste, of trees, earth, palisades, wagons, or anything that will obstruct the progress or attack of an enemy. It is usually an obstruction formed in streets to block an enemy's access.
2. Any bar, obstruction, or means of defense. Such a barricade as would greatly annoy, or absolutely stop, the currents of the atmosphere. Derham.
1 other Webster entry under this spelling
Barricade, v. t. [imp. & p. p. Barricaded; p. pr. & vb. n. Barricading.]
To fortify or close with a barricade or with barricades; to stop up, as a passage; to obstruct; as, the workmen barricaded the streets of Paris. The further end whereof [a bridge] was barricaded with barrels. Hakluyt.
Shades of meaning
Fernald has no entry of its own for barricade; he lists it under barrier, obstruct.
Where he writes about it:
Barricade has become practically a technical name for an improvised street fortification, and, unless in some way modified, is usually so understood. — from barrier