unitasker

plural unitaskers

1. A person who does a single thing at a time.

   Even with scientific validation at his fingertips, Mr. Leleux frets that the Stanford study may have been done “by a bitter unitasker like me who wants to validate his own existence.”

   2009 August 30, Ruth Pennebaker, “The Mediocre Multitasker”, in New York Times

2. A tool, particularly a kitchen utensil, which is useful only for performing a particular, specialized task

   Bird’s beak: This style [of paring knife] has a shorter, curved blade that’s specifically designed for turning vegetables. It is really a unitasker and has no room on our knife strip at home.

   2016 March 4, Lesley Stockton, “The Best Paring Knife”, in The Sweethome, archived from the original on 24 Mar 2016