This post is one in a series on prominent company nicknames. See all 25, and share your thoughts and memories about Big Blue below in the comments.

Although there shall probably always remain unanswered speculation as to exactly how the nickname came to be, most people in business or industry today know, when you mention Big Blue, you're talking about IBM, International Business Machines Corp. (NYSE: IBM). It's a name that invokes a respect of power, much in the same way that motorists pull aside for a fire engine or stop for a moving train. As reflected in the three letter company logo, Big Blue is solid and steady, yet quite on the move.

People have attributed the company nickname to a past company dress code, when employees were required to wear white shirts and most of them wore blue suits. That theory seems a bit shallow to me. Besides, that policy was done away with in the 1990s by CEO, Lou Gerstner. Since that time, I haven't noticed anyone calling IBM, Big Business Casual.

A second theory about the company moniker follows a more logical theme. It relies on the fact that IBM uses blue for its company logo and equipment, blue being a color that denotes strength. People also naturally associate blue with largeness, similar to the sky, the oceans, and even outer space. When used in context, people just know what big company you're talking about when you use the name. For instance, if I asked my step-mom; "How are you and Big Blue doing?" she'd immediately know I was referring to one of her independent engineering contracts with IBM.