The Collaborative International Dictionary of English v.0.48:

Nook \Nook\ (n[oo^]k; 277), n. [OE. nok; cf. Gael. & Ir. niuc.]
   A narrow place formed by an angle in bodies or between
   bodies; a corner; a recess; a secluded retreat.
   [1913 Webster]

         How couldst thou find this dark, sequestered nook?
                                                  --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nook
    n 1: a sheltered and secluded place
    2: an interior angle formed by two meeting walls; "a piano was
       in one corner of the room" [syn: corner, nook]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "nook":
   L, alcove, angle, apex, asylum, bay, bend, bifurcation, bight,
   bolt-hole, cache, cant, carrel, cavity, chevron, coin, concealment,
   corner, cove, cover, covert, coverture, crack, crank, cranny,
   crevice, crook, crotchet, cubby, cubbyhole, cubicle, dark corner,
   deflection, den, dogleg, dugout, elbow, ell, fork, foxhole,
   funk hole, furcation, hideaway, hideout, hidey hole, hiding,
   hiding place, hole, hook, inflection, inglenook, knee, lair, nest,
   niche, opening, oriel, pitchhole, point, quoin, recess, recession,
   refuge, retreat, roomlet, sanctuary, secret place, snuggery, stash,
   swerve, undercovert, veer, vertex, zag, zig, zigzag