Definitions of sustain:

• verb:   admit as valid

  Example: "The court sustained the motion"

• verb:   supply with necessities and support

  Example: "She alone sustained her family"

• verb:   lengthen or extend in duration or space

  Example: "We sustained the diplomatic negociations as long as possible"

• verb:   undergo (as of injuries and illnesses)
• verb:   establish or strengthen as with new evidence or facts
• verb:   provide with nourishment

  Example: "We sustained ourselves on bread and water"

• verb:   be the physical support of; carry the weight of