Definitions of strain:

• noun:   an intense or violent exertion
• noun:   (physics) deformation of a physical body under the action of applied forces
• noun:   injury to a muscle (often caused by overuse); results in swelling and pain
• noun:   (psychology) nervousness resulting from mental stress

  Example: "His responsibilities were a constant strain"

• noun:   the act of singing
• noun:   a lineage or race of people
• noun:   pervading note of an utterance
• noun:   a special variety of domesticated animals within a species

  Example: "He created a new strain of sheep"

• noun:   difficulty that causes worry or emotional tension

  Example: "She endured the stresses and strains of life"

• noun:   (biology) a group of organisms within a species that differ in trivial ways from similar groups

  Example: "A new strain of microorganisms"

• noun:   an effortful attempt to attain a goal
• noun:   a succession of notes forming a distinctive sequence
• verb:   use to the utmost; exert vigorously or to full capacity

  Example: "Don't strain your mind too much"

• verb:   stretch or force to the limit

  Example: "Strain the rope"

• verb:   make tense and uneasy or nervous or anxious;
• verb:   rub through a strainer or process in an electric blender
• verb:   test the limits of
• verb:   alter the shape of (something) by stress
• verb:   to exert much effort or energy

  Example: "Straining our ears to hear"

• verb:   remove by passing through a filter
• verb:   separate by passing through a sieve or other straining device to separate out coarser elements
• name:  A surname (rare: 1 in 25000 families; popularity rank in the U.S.: #3399)