receptor

noun

1. A protein on a cell wall that binds with specific molecules so that they can be absorbed into the cell in order to control certain functions.

   “In the target organ, the drug is recognised by ‘receptors’. These are large molecules, usually proteins, to which the drug binds tightly and with a high degree of specificity.”

   “White blood cells of the immune system, the gut and the spleen also have another type of cannabinoid receptor, known as CB2.”

2. Any specialized cell or structure that responds to sensory stimuli.
3. (obsolete)One who receives something or someone; in particular, one who harbors a fugitive.

   “[…] fewe that were there did spend the same daie abowte the searchinge out of sundrye that were receptors of ffelons, where we fownd a greate manye aswell in London, Westminster, Sowthwarke, as in all other places abowte the same.”

   “The kind Receptors of the Fugitiues after the Detection.”

   “An act […] Against pyrats, their assistors or abettors, out-traidors or receptors, against breakers of the admirall's arrestments and attachments against goods forbidden,”