Griego
Griego (Greek) is the European language spoken by the ancient people of Greece. Many Spanish words have their origin in Greek. For example, gramática ("grammar") comes from Greek gramma ("written, letter"), and etimología ("etymology") comes from Greek etymología ("true meaning").
Greek roots show up in both Spanish and English, usually in the same technical or scientific words — for example, telescopio / "telescope", biología / "biology", demócrata / "democrat". If you recognize one, you usually recognize the other.