Nuclear means "of or belonging to the nucleus (or center) of something". Which pronunciations of "nuclear" are commonly acceptable is a matter of some debate and amusement; see Nucular for an example.
- Where the subject is the nucleus of an atom, "nuclear" usually refers to nuclear physics.
- In biology, it refers to the cell nucleus.
- The term nuclear is also sometimes used to refer to a family type. See: nuclear family.