A unitasker is a tool or device that does only one thing. Before it meant that, it was a dismissive term for a person who does one job at a time before moving to the next, the opposite of a multitasker.
Definitely a unitasker
It’s one of those slow-burn words that seems to be creeping up on us in a variety of fields, becoming accepted because it’s a useful term of abuse to describe those gadgets we buy because they seem like a good idea at the time. This is despite experience teaching us that their advantages don’t justify their cost or the space they take up or that a general-purpose item could do the job as well. It’s used in particular for specialist kitchen gadgets (electric gravy boat warmers, strawberry slicers, watermelon knives) and odd computing contraptions (USB foot warmers). Unitasker has been popularised by the American TV chef Alton Brown and the website unclutterer.com.
Not all unitaskers are bad, of course; some of them are invaluable and their limitations are a strength, not a weakness. What’s wrong with a fire extinguisher? It does one job well. (OK, you can use it to prop the door open or brain a burglar, but we’re talking about intended uses here.) And one person’s useless unitasker is another’s onion-ring holder or USB fragrance oil burner.
While I’m skeptical of tools intended for only one purpose, I like the Kindle because it’s a unitasker. You can’t really use it for the Web or Twitter or e-mail: It’s for reading and that’s it.
Macworld; Dec. 2010.