In text, a character or combination of characters appearing between spaces or between a space and a punctuation mark, usually representing a spoken word. 2. The number of bits that can be stored in one CPU register in a computer. The size of a word is usually the width of the data bus. Since most bytes in present-day computers are eight bits, a word is usually a multiple of eight; a common size is two eight-bit bytes (16 bits) or four eightêes (32 bits). Larger computers may have 64-bit words. The size of word that can be transmitted affects the speed of the computer.