Apt means appropriate or suitable for the circumstances. Aptly is the adverb and aptness is the noun. However, aptful is not a word.

-noun 1. the practice or art of using language with fluency and aptness.

2. eloquent language or discourse: a flow of eloquence.

Those letters will spell aptness.

appropriateness, competence, readiness, eligibility, suitability, aptness

health, strength, vigour, wellness, robustness

Apt means appropriate or suitable for the circumstances. Aptly is the adverb and aptness is the noun. However, aptful is not a word.