How to spell THANKFU correctly?

For the common misspelling "thankfu", there are a couple of correct suggestions to rectify this error. One option is to simply add the missing "l" at the end, resulting in "thankful". Alternatively, one could replace the "fu" with "ful", leading to the correct spelling "thankful."

• thank
• Thanked After receiving her gift, she thanked her friend for the thoughtful gesture.
• thankful
• thanks

Attenttion

• attention
• attentions
• attenuation
• inattention