Gerund/uncountable noun meaning ‘the act or process of propelling’.
propellinggerundium / partizip präsens Present-participle adjective meaning ‘that propels’; more precise label than generic ADJECTIVE.
The propelling force of the engine was impressive.
Движущая сила двигателя была впечатляющей.
The propelling mechanism of the machine was malfunctioning.
Толкающий механизм машины не работал.