Incorrect spelling


Incorrect spelling, explanation: this is an incorrect form since the adjective suffix -ful is written with just one l. It is usually mistaken with the word full, which is also quite close in meaning (suffix -ful gives the meaning of full of). Helpfull is however incorrect, and the correct form is helpful, with one l as the right spelling of the suffix points to.

Correct spelling


Correct spelling, explanation: adjective suffix -ful is very often mistaken in spelling with the word full, with which it is actually quite closely connected in meaning. The suffix -ful gives the meaning full of (or characterized by so it can be mistaken with the word spelling itself. However helpful as any other adjective with this suffix is spelled with one l at the end; therefore helpfull is an incorrect form.

Definition of helpful:
adjective, one that helps a lot; is willing to help at all times
Jessica is such a helpful girl; she never leaves a friend without help.
Flight attendants should be helpful, supportive, and nice.