first thing

first thing (not comparable)

1. Early in the morning.

   I'll meet you first thing at the station.

2. Straight away, very soon.
   • 2009, Alex J. Packer, Bringing Up Parents: The Teenager's Handbook, →ISBN:

     I'll do it first thing after school tomorrow.

   • 2012, Cd Harper, And Face the Unknown: The Journey of a Lincoln-freed Colored, →ISBN:

     You had to see it first thing, 'cause it was the first thing that caught the eye.

   • 2013, Nelson Searcy, ‎Jennifer Dykes Henson, The Renegade Pastor: Abandoning Average in Your Life and Ministry, →ISBN, page 2013:

     Whatever it is, getting it out of the way is crucial to your forward momentum. So, to borrow a phrase from Nike, just do it—and do it first thing.

first thing (plural first things)

1. The basic idea of how to do something.

   I would help you, but I don't know the first thing about gardening.

2. Used other than with a figurative or idiomatic meaning: see first,‎ thing.
   • 1913, Joseph C. Lincoln, chapter 1, in Mr. Pratt's Patients:

     I stumbled along through the young pines and huckleberry bushes. Pretty soon I struck into a sort of path that, I cal'lated, might lead to the road I was hunting for. It twisted and turned, and, the first thing I knew, made a sudden bend around a bunch of bayberry scrub and opened out into a big clear space like a lawn.

• first thing at OneLook Dictionary Search