hol·low 
(hŏlō)
(hŏlō)adj. hol·low·er, hol·low·est
1. Having a cavity, gap, or space within: a hollow wall.
2. Deeply indented or concave; sunken: "His bearded face already has a set, hollow look" (Conor Cruise O'Brien).
3. Without substance or character: a hollow person. See Synonyms at vain.
4. Devoid of truth or validity; specious: "Theirs is at best a hollow form of flattery" (Annalyn Swan).
5. Having a reverberating, sepulchral sound: hollow footsteps.
n.
1. A cavity, gap, or space: a hollow behind a wall.
2. An indented or concave surface or area.
3. A void; an emptiness: a hollow in one's life.
4. A small valley between hills or mountains.
v. hol·lowed, hol·low·ing, hol·lows
v.tr.
1. To make hollow: hollow out a pumpkin.
2. To scoop or form by making concave: hollow out a nest in the sand.
v.intr.
To become hollow or empty.
[Middle English holwe, holowe, from holgh, hole, burrow (influenced by hole, hollow), from Old English holh; see kel-1 in the Appendix of Indo-European roots.]
hollow·ly adv.
hollow·ness n.