Related Clues:

• Vent
• Kind of pressure
• Hole in the head
• Bone cavity
• Sweat source
• Leaf opening
• Opening in a sweater?
• It's right under your nose
• Mouth
• Breathing space
• Study intently (with "over")
• Skull cavity
• Kind of headache
• Scrutinize (with ''over'')
• Read carefully