Abarim Publications' online Biblical Hebrew Dictionary
Linguists have identified two separate root-verbs שעע (sha'a'), which may not be all that dissimilar, and one root-verb שעה (sha'a), which may have something to do with שעע (sha'a' I):
The verb שעע (sha'a' I) means to smear over and is used in the Bible solely to describe smeared-over or blinded eyes. It occurs half a dozen times (Isaiah 6:10, Isaiah 29:9), although in some instances it isn't clear which verb we're looking at.
The verb שעע (sha'a' II) means to sport or delight in, although perhaps (BDB Theological Dictionary seems to suggest) the action of smearing something over may lead to the idea of smoothing something out, which then may lead to delight, or in other words: there might not be two distinct root-verbs at all, but one. But some more or less clear instances of to delight are Isaiah 29:9, Isaiah 66:12 and Psalm 119:70.
This verb comes with one derivative: the masculine noun שעשעים (sha'ashu'im), which is a plural or intensive word meaning delight (Proverbs 8:31, Psalm 119:24). This word is sometimes also written as שועים (sho'im; Jeremiah 31:20, Proverbs 8:30), which brings the form very close to the verbs ישע (yasha) and שוע (shawa; follow the link for more info on both).
Like שעע (sha'a), the verb שעה (sha'a) also has something to do with the eyes, as it means to gaze (Genesis 4:5, Psalm 39:14). In some cases it's not clear at all which of these two verbs we're dealing with (Isaiah 32:3 for instance).