A spin-off is a meme which extracts itself from a popular idea and becomes an entity in its own right, rather like a Frankingstein. TV spinoffs include:

• Frasier (Cheers)
• Mork and Mindy (Happy Days, maybe Laverne and Shirley)
• Wiggum PI, Simpson Family Smile Time Variety Hour, the Love Test Grandpa (do'h!)
• the justice friends (dexter's laboratory)
• Knots Landing (Dallas)
• Caravan of Courage (you know this one)

An entity derived from a pre-existing entity. Lucent was spun off from American Telephone and Telegraph; the DOJ could possibly spin off separate companies from The Borg as an antitrust remedy. In television, it involves creating a new show from a popular one - Daria came from Beavis and Butthead; The Simpsons was based on a segment of The Tracey Ullman Show.