The Collaborative International Dictionary of English v.0.48:

Yex \Yex\, n. [AS. geocsa a sobbing, hiccough. Cf. Yex, v. i.]
   A hiccough. [Written also yox, and yux.] [Obs. or Prov.
   Eng.] "The excessive yex." --Holland.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Yex \Yex\, v. i. [OE. [yogh]exen, yesken, AS. giscian to sob.]
   To hiccough. [Written also yox, yux.] [Obs. or Prov.
   Eng.]
   [1913 Webster]

         He yexeth and he speaketh through the nose. --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

Yox \Yox\, v. i.
   See Yex. [Obs.] --Chaucer.
   [1913 Webster]