The phrase "large number" has a subjective meaning, which is unsatisfactory for googologists because their studies rely on the definition of the term. Informally, it could be defined as "a number larger than any one used in everyday life." To a politician, this may be a trillion euros; to a cosmologist, 1026 meters.
Sbiis Saibian suggested defining a large number as any real number greater than 1, offering the alternate term superuniary number. Small numbers would be those smaller than 1. This definition has the advantage that it makes the small numbers the reciprocals of the large ones.However it essentially eliminates the distinction between discussing numbers as a whole and discussing large numbers per se.