According to wikipedia:
The infinitive of a verb is its basic form with or without the particle to: therefore, do and to do, be and to be, and so on are infinitives
My interpretation is it the action form of a verb. I.E. to do, to run, to live, to love
The same forms can be used for the other construct prefixes: ב,כ,ל,מ
Here are the patterns to form gerunds in Hebrew:
| Binyan | feeling | pattern | Notes | example root | example |
| פָּעָל | Root | לִפְעֹל | Remember the dagesh qal in the ע if needed after a shva | ספר | לִסְפֹּר |
| פִּעֵّל | Intensive | לְפַעֵל | Dagesh forte in ע | ספר | לְסַפֵּר |
| הִפְּעִיל | Causative | לְהַפְעִיל | Remember the dagesh qal in the ע if needed after a shva | כתב | לְהַכְתִּיב |
| הִתְפַּעֵّל | Reflexive | לְהִתְפַּעֵל | dagesh foret in ע Remember the dagesh qal in the פ if needed after a shva | כתב | לְהִתְכַּתֵּב |
| נִפְעַל | Passive | לְהִפַָּעֵל | dagesh in פ Due to the removal of the נ | כנס | לְהִכָּנֵס |