To break down the word pangaea, you can split it into "pan" and "gaea". "Pan" means whole, and "gaea" means Earth in Greek, so pangaea means "all lands".
Alfred Wegener in the year 1912 gave a proposition that all the continents that we see today were once compressed together into one large supercontinent/protocontinent.
He named this supercontinent as Pangea which means "all lands".
The word was derived from an ancient Greek word wherein pan = all and Gaia=land.
