• reine,
• rhine,
• rein,
• ehein,
• dhein,
• fhein,
• 5hein,
• 4hein,
• rgein,
• rbein,
• rjein,
• ryein,
• rhwin,
• rhsin,
• rhdin,
• rhien,
• rheyn,
• rheen,
• Rheyne,
• Rhyeen

• rhyme,
• rein,
• rhino,
• Rhona,
• rhynia,
• rhone,
• rhyne,
• rhine.

The adjective form of the word "rhein" is "rheinic".

The plural form of the word "rhein" is "rheine"

The singular form of the word "rhein" is "rhein". Note that "rhein" is already a singular noun, specifically referring to the Rhine River in Western Europe.