🔼The name Thomas in the Bible
The one and only Thomas of the Bible is one of the Twelve Apostles of Jesus Christ. The Book of Acts and all four gospels mention him but only John gives him an active role (and submits his Greek name: Didymus — John 11:16).
His first recorded words are: "Let us also go, that we may die with Him" (John 11:16), but because of his dubiosity about his colleagues' enthusiasm concerning the resurrected Christ, tradition has dubbed him Doubting Thomas. What tradition was slow to pick up on is that Thomas was under standing orders by Christ to not believe when people reported a Messiah sighting (Matthew 24:23-26).
When Jesus shows Himself to Thomas too, he doesn't in any way rebuke him but calls him blessed for having seen Him (John 20:29). Jesus also calls blessed those who somehow believe in Him through a process that involves experiencing Him but not seeing Him. It has nothing to do with believing enthusiastic folks who spread rumors.
The name Thomas appears 11 times in the New Testament; see full concordance.
🔼Etymology of the name Thomas
The name Thomas means Twin. Note that even though the name Thomas became very popular, it wasn't in New Testament times. BDB Theological Dictionary submits that this name also existed in Phoenician but it's not clear whether that was pre or post Biblical Thomas. Perhaps the name Thomas (and Didymus too, for that matter) was a Biblical invention, and it certainly caused the name's huge popularity.