/riˈseptər/
Noun
1. (Physiology) An organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve. (Google Dictionary)
2. A nerve ending that senses changes in light, temperature, pressure, etc., and causes the body to react in a particular way. (merriam-webster.com)
3. A cell or group of cells that receives stimuli : sense organ. (merriam-webster.com)
4. A chemical group or molecule (as a protein) on the cell surface or in the cell interior that has an affinity for a specific chemical group, molecule, or virus. (merriam-webster.com)
5. A cellular entity (as a beta-receptor or alpha-receptor) that is a postulated intermediary between a chemical agent (as a neurohormone) acting on nervous tissue and the physiological or pharmacological response. (merriam-webster.com)
Word origin: From Old French receptour or directly from Latin receptor, agent noun from recipere