noun

• (obsolete) An assistant to a head teacher or schoolteacher; an assistant teacher.
  "[H]e defrayed the expence of his entrance, and left him in the particular care and inspection of the usher, who […] though obliged by the scandalous administration of fortune to act in the character of an inferior teacher, had by his sole capacity and application, brought the school to that degree of reputation which it never could have obtained from the talents of his superior."
• (dated, derogatory) Any schoolteacher.

verb

• (figurative) To precede; to act as a forerunner or herald.
  "Thus the Harvard poets and wits ushered The New England Courant out of existence."
• (figurative) To lead or guide somewhere.
  "McCoist unexpectedly ushered back a defender of his own with Kirk Broadfoot taking over from Steven Whittaker. There was, of course, another change, Kyle Bartley stepping in at centre-half to replace suspended Dorin Goian."