Definitions of observe:

• verb:   watch attentively

  Example: "Please observe the reaction of these two chemicals"

• verb:   celebrate, as of holidays or rites

  Example: "Observe Yom Kippur"

• verb:   conform one's action or practice to
• verb:   observe correctly or closely
• verb:   discover or determine the existence, presence, or fact of
• verb:   follow with the eyes or the mind
• verb:   make mention of

  Example: "She observed that his presentation took up too much time"

• verb:   observe with care or pay close attention to
• verb:   show respect towards