Abarim Publications' online Biblical Hebrew Dictionary
The meaning of the root שמש (sms) is unknown, although reflections of it occur across the Semitic language spectrum. And it yields a very common derivation: the feminine noun שמש (shemesh), meaning sun.
Our noun is introduced in the Bible in Genesis 15:2. In other words: contrary to common belief, the sun is not mentioned in the creation account (and neither is the moon), and here at Abarim Publications we believe that the creation week is not about the creation of the solar system (see for more details our celebrated Introduction to Scripture Theory).
The sun is mentioned well over a hundred times in the OT, in all kinds of usages. Surrounding nations worshipped the sun but Israel was strictly told not to (Deuteronomy 4:19), although respectful parallels with the Living God were certainly drawn (Psalm 84:11). The sun is a mighty creature but ultimately God has it in His hands (Joshua 10:13 but also Exodus 10:21-29).
It should be noted that the proverbial sunny impression of the sun in our culture is not shared by that of ancient Israel. In an agricultural society such as that of Israel, the weather was viewed differently than in our industrial age. A sunny day was not greeted with more or less enthusiasm than a rainy day. The motion of the sun was the prime measure of time. The sun stood symbol for God's glory (Psalm 148:3) but it could kill when there was no shelter (Jonah 4:8).