• comon effort,
• common effrt,
• comman effort,
• commn effort,
• common effert,
• commom effort,
• common effott,
• common efort,
• commin effort

The adjective form of "common effort" is "collaborative".

The plural form of the word "common effort" is "common efforts".

The singular form of the word "common effort" is "common effort". The word remains the same in both singular and plural form.