(cytology) A cell in the brain, such as a neuron or a glial cell. / (colloquial) neuron / (humorous) -- taken as a unit of intelligence

(cytology) A cell of the nervous system which conducts nerve impulses; a neuron.

(hematology, cytology) Any of the cells normally found in blood, namely erythrocytes and leukocytes, sometimes including the platelets.

A group of people (sleepers) who inconspicuously remain dormant in a community until activated, by a prearranged signal, to perform acts of espionage, sabotage, and/or terrorism.

(cytology) The semipermeable membrane that surrounds the cytoplasm of a cell.

A spice ingredient used in cooking consisting of ground celery seed and salt.

The seed of the plant celery, Apium graveolens, used as a seasoning in cooking.

The highest altitude at which an aircraft may fly due to physical factors, such as low air density.

(energy) An electrochemical device in which the intrinsic chemical free energy of fuel and oxidant is catalytically converted to direct current energy.

(cytology) Any normal cell of an organism that is not involved in reproduction; a cell that is not on the germline.