1911 Encyclopædia Britannica/Merger

MERGER (Fr. merger, to sink), in law, the sinking or “drowning” of a lesser estate in a greater, when the two come together in one and the same person without any intervening estate. In order to effect a merger the two estates must vest in the same person at the same time, must be immediately expectant one on the other, and the expectant estate must be larger than the preceding estate. The term is also used for the extinguishment of any right, contract, &c., by absorption in another, e.g. the acceptance of a higher security for a lower, or the embodying of a simple contract in a deed.