Word / formMeaning / explanation
التَّبَسُّمsmiling.
التَّفَكُّهenjoying fruit or light amusement, by context.
التَّثَبُّتverifying carefully or becoming firmly established.
التَّعَجُّلhurrying.
These source examples illustrate the تَفَعُّل verbal-noun pattern: initial tāʾ and a doubled middle radical.
Tafaʿʿul may describe adopting a state, acting deliberately, or an action affecting the subject, depending on the word. It would be inaccurate to assign precisely the same semantic value to taʿajjul and tathabbut.