Abarim Publications' online Biblical Hebrew Dictionary
There are two roots with the form פסס (pss) in Biblical Hebrew, and one with the comparable form פשה (psh), which appears to have to do with one of the roots פסס (pss):
The root פשה (pasa) means to spread. It occurs only in Leviticus 13 and 14, and only in connection with leprosy and similar eruptions. The letters שׂ (sin) and ס (samekh) often interchange, and this verb appears to be related to root פסס (pss).
The assumed root פסס (pss I) isn't used in the Bible but two derivations remain:
- The masculine noun פס (pas), often thought to denote the flat of the hand or foot. In the Bible this noun is only used in conjuncture with a garment (Joseph's tunic - Genesis 37:3, or Tamar's robe - 2 Samuel 13:18), which is then assumed to have reached to the hand palms and the foot soles. Modern translations appear to interpret the spreading conveyed by this verb not so much in the spatial sense but rather in the way it looked; NAS figures that Joseph's tunic was "varicolored," and NIV has "richly ornamented". This may make perfect sense in view of this root's other derivative.
- The feminine noun פסה (pissa), which meaning is as obscure as its root. It's used only once, in Psalm 72:16, and probably means abundance, or abundantly spread out.
The verb פסס (pasas II) means to disappear or vanish. It's used only once, in Psalm 12:1, where the psalmist laments that the faithful disappear from among men. Since faithfulness requires social cohesion (to establish and retain standards to be faithful to), the disappearance of these faithful was likely due to their density in society, which results from them being spread out.