A lapse is a gift in a will that is not given because the beneficiary dies before the person who made the will does. In such cases, the lapsed gift becomes a part of the residual estate. However, if a state has an anti-lapse law, then the gift could go to a different heir of the will writer (if he or she has other heirs).
Gifts made in wills can be quite substantial. For example, houses, cars, jewelry, money, etc. can all be passed along in wills. So, gifts can present a significant legal problem if a lapse occurs. For example, if a man passes his house along to his eldest son in a will, but that son dies a month before the man does, this can be a big problem. What will happen to the house if such a situation occurs will depend on whether or not the state has an anti-lapse law, and whether or not the man has any other heirs.