Abarim Publications' online Biblical Hebrew Dictionary
The verb שאן (sha'an) basically means to be undisturbed: to be comfy and unmoved to the limit of being lethargic. It occurs less than half a dozen times. YHWH promises that Jacob shall return and be comfy and at ease, and no one will be able to scare him (Jeremiah 30:10). Likewise Solomon declares that he who listens to Hochma shall be comfy and not fear evil (Proverbs 1:33). Moab has been comfy since childhood, and that's why he hasn't lost his flavor or aroma (Jeremiah 48:11). Job wishes he had died at birth, to be comfy with the prisoners (of the realm of death; Job 3:18).
This verb's sole derivatives is the adjective שאנן (sha'anan), meaning unmoved in the sense of being perpetual (Jerusalem: Isaiah 33:20; tents of prospering destroyers who provoke God: Job 12:6), or inattentive (Amos 6:1), complacent (Isaiah 33:9) or arrogant (2 Kings 19:28).