Definitions of peep:

• noun:   a secret look
• noun:   the short weak cry of a young bird
• verb:   cause to appear

  Example: "He peeped his head through the window"

• verb:   look furtively

  Example: "He peeped at the woman through the window"

• verb:   appear as though from hiding

  Example: "The new moon peeped through the tree tops"

• verb:   speak in a hesitant and high-pitched tone of voice
• verb:   make high-pitched sounds; of birds