In host–guest chemistry, a carcerand () is a host molecule that completely entraps its guest (which can be an ion, atom or other chemical species) so that it will not escape even at high temperatures. This type of molecule was first described in 1985 by Donald J. Cram and coworkers. The complexes formed by a carcerand with permanently imprisoned guests are called carceplexes.
In contrast, hemicarcerands allow guests to enter and exit the cavity at high temperatures but will form stable complexes at ambient temperatures. The complexes formed by a hemicarcerand and a guest are called hemicarceplexes.