1. [n]  lining consisting of material with a high melting point; used to line the inside walls of a furnace
2. [adj]  resistant to authority or control; "as refractory as a mule"
3. [adj]  stubbornly resistant to authority or control; "a fractious animal that would not submit to the harness"; "a refractory child"
4. [adj]  marked by stubborn resistance to and defiant of authority or guidance; "a recalcitrant teenager"; "everything revolves around a refractory individual genius"
5. [adj]  (medicine) not responding to treatment; "a stubborn infection"; "a refractory case of acne"

REFRACTORY is a 10 letter word that starts with R.

1. \Re*frac"to*ry\ (-r?), a. [L. refractorius, fr.
   refringere: cf. F. refractaire. See {Refract}.]
   1. Obstinate in disobedience; contumacious; stubborn;
      unmanageable; as, a refractory child; a refractory beast.
   
            Raging appetites that are Most disobedient and
            refractory.                           --Shak.
   
   2. Resisting ordinary treatment; difficult of fusion,
      reduction, or the like; -- said especially of metals and
      the like, which do not readily yield to heat, or to the
      hammer; as, a refractory ore.
   
   Syn: Perverse; contumacious; unruly; stubborn; obstinate;
        unyielding; ungovernable; unmanageable.
   
   

2. \Re*frac"to*ry\, n.
   1. A refractory person. --Bp. Hall.
   
   2. Refractoriness. [Obs.] --Jer. TAylor.
   
   3. OPottery) A piece of ware covered with a vaporable flux
      and placed in a kiln, to communicate a glaze to the other
      articles. --Knight.