Cisco has become a major major player in the networking business, and are presently even trying to raise their visibility in the consumer mind space too.
Critics might point out that it sounds very similar to Crisco, the well-known cooking oil.
Trademark educators and lawyers (and namers like us) might point out that it is phonetically equivalent (and therefore the same) to other trademarks like Sysco and Sisco, both of which are also registered trademarks. But Sysco is a food distribution company (one of biggest in USA supplying restaurants) and Sisco is a document shredding company.
With these alternative spellings, it is not hard to figure out where their name originate. The clue as to how Cisco got its name is in their logo! Yes, that is a representation of the golden gate bridge in San Francisco, and the name is nothing more than a truncation of Francisco!
Wow.. the biggest name in networking. All those propeller head engineers and their name means nothing! Of course, as a brand it now stands for a great promise and is well known, and no one questions it.
PS Notice the name is half of San Francisco, so the logo is only half a bridge (cut lengthways)!
Motto:
If you are careful, there is trademark room for another close and similar name in many fields, but be careful how close to the flame you fly.