- An insect of the order Hemiptera (the "true bugs").
- Any insect or spider may often be called a bug.
- These flies are a bother. I’ll get some bug spray and kill them.
- A problem that needs fixing, especially in computing.
- The computer program has a bug in it.
- A contagious illness caused by bacteria or a virus.
- He’s got the flu bug.
- An enthusiasm for something; an obsession.
- I think he’s a gold bug, he has over 10,000 ounces in storage.
- to catch the skiing bug
- An electronic listening device.
- We installed a bug in her telephone.
- A small or invisible image on a webpage that is used to track persons who viewed it.
- He suspected the image was a web bug used for determining who was visiting the site.
- A small, usually transparent or translucent image placed in a corner of a television program to indicate what network or cable channel is televising it.
- He did not like the network bug that appeared onscreen.
- Figurative – A manually positioned marker in flight instruments.
- A semi-automated telegraph key.