[1] : The Collaborative International Dictionary of English v.0.48

strain \strain\, v. t. imp.  p. p. strained; p. pr.  vb. n.
   straining. of. estraindre, estreindre, f. 'etreindre,
   l. stringere to draw or bind tight; probably akin to gr. ? a
   halter, ? that which is squeezwd out, a drop, or perhaps to
   e. strike. cf. strangle, strike, constrain, district,
   strait, a. stress, strict, stringent.
   1. to draw with force; to extend with great effort; to
      stretch; as, to strain a rope; to strain the shrouds of a
      ship; to strain the cords of a musical instrument. "to
      strain his fetters with a stricter care." --dryden.
      1913 webster

   2. mech. to act upon, in any way, so as to cause change of
      form or volume, as forces on a beam to bend it.
      1913 webster

   3. to exert to the utmost; to ply vigorously.
      1913 webster

            he sweats,
            strains his young nerves.             --shak.
      1913 webster

            they strain their warbling throats
            to welcome in the spring.             --dryden.
      1913 webster

   4. to stretch beyond its proper limit; to do violence to, in
      the matter of intent or meaning; as, to strain the law in
      order to convict an accused person.
      1913 webster

            there can be no other meaning in this expression,
            however some may pretend to strain it. --swift.
      1913 webster

   5. to injure by drawing, stretching, or the exertion of
      force; as, the gale strained the timbers of the ship.
      1913 webster

   6. to injure in the muscles or joints by causing to make too
      strong an effort; to harm by overexertion; to sprain; as,
      to strain a horse by overloading; to strain the wrist; to
      strain a muscle.
      1913 webster

            prudes decayed about may track,
            strain their necks with looking back. --swift.
      1913 webster

   7. to squeeze; to press closely.
      1913 webster

            evander with a close embrace
            strained his departing friend.        --dryden.
      1913 webster

   8. to make uneasy or unnatural; to produce with apparent
      effort; to force; to constrain.
      1913 webster

            he talks and plays with fatima, but his mirth
            is forced and strained.               --denham.
      1913 webster

            the quality of mercy is not strained. --shak.
      1913 webster

   9. to urge with importunity; to press; as, to strain a
      petition or invitation.
      1913 webster

            note, if your lady strain his entertainment. --shak.
      1913 webster

   10. to press, or cause to pass, through a strainer, as
       through a screen, a cloth, or some porous substance; to
       purify, or separate from extraneous or solid matter, by
       filtration; to filter; as, to strain milk through cloth.
       1913 webster

   to strain a point, to make a special effort; especially, to
      do a degree of violence to some principle or to one's own
      feelings.

   to strain courtesy, to go beyond what courtesy requires; to
      insist somewhat too much upon the precedence of others; --
      often used ironically. --shak.
      1913 webster
see also:
strained straining strangle strike constrain district 
strait stress strict stringent to strain a point 
to strain courtesy 

Strain >> S Words
Strain, definition of term: Strain
strain_pag1.html

Courtesy >> C Words
Courtesy, definition of term: Courtesy
courtesy_pag1.html