im·per·cep·ti·ble 
(ĭm′pər-sĕptə-bəl)
(ĭm′pər-sĕptə-bəl)adj.
1. Impossible or difficult to perceive by the mind or senses: an imperceptible drop in temperature.
2. So subtle, slight, or gradual as to be barely perceptible: an imperceptible nod.
im′per·cep′ti·bili·ty, im′per·cepti·ble·ness n.
im′per·cepti·bly adv.
- phospholipid
- phosphonium
- phosphoprotein
- phosphor
- phosphor bronze
- phosphoresce
- phosphorescence
- phosphorescent
- phosphorescently
- phosphoric
- phosphoric acid
- phosphorism
- phosphorite
- phosphorous
- phosphorous acid
- phosphorus
- phosphorylase
- phosphorylate
- phosphorylation
- phosphorylative
- phot
- phot-
- phot-
- photic
- photo