Ajedrez (Spanish for “chess”) sounds nothing like the English chess, so they can’t be first cousins… right?
Wrong. The Spanish “j” sound — pronounced with an Arabic-ish throat-clearing sound — was originally pronounced with a “sh” or “ch” sound. The arabic influence changed the pronunciation to be closer to the arabic: see sherry/jerez, for example.
Ajedrez and Chess are another example of this same interesting pattern. Try to imagine the “j” in ajedrez with a ch- sound and you almost get chess.
Both, curiously, come from the same Sanskrit word for the game: chaturanga (so the English ch- is thus preserved closer to the original sound — English didn’t have the arabic influence that Spanish did). And these came to both languages via the Persian, chatrang. The traders and travelers, after all, are the ones who change languages.