• xharles river,
• vharles river,
• fharles river,
• dharles river,
• cgarles river,
• cbarles river,
• cnarles river,
• cjarles river,
• cuarles river,
• cyarles river,
• chzrles river,
• chsrles river,
• chwrles river,
• chqrles river,
• chaeles river,
• chadles river,
• chafles river,
• chatles river,
• cha5les river,
• cha4les river

The plural form of "Charles River" is "Charles Rivers".

The singular form of the word "Charles River" is "Charles River". It remains the same in both singular and plural forms.