1. Computers, operating systems, or software programs capable of transferring data 32-bits at a time. With computer processors, (e.g. 80386, 80486, and Pentium) they were 32-bit processors, which means the processor were capable of working with 32 bit binary numbers (decimal number up to 4,294,967,295). Anything larger and the computer would need to break up the number into smaller pieces.
A good example of the first 32-bit operating system is OS/2 and Windows NT, often versions of Windows that are 32-bit are referred to as WOW32. Today, 32-bit computers and operating systems are being replaced by 64-bit computers and operating systems such as 64-bit versions of Windows 7.
2. 32-bit can also refer to the amount of colors a video card is displaying. 32-bit is the same as 16.7 million colors (24-bit color with an 8-bit alpha channel).