מָרַר mârar (H4843)

to be (causatively, make) bitter (literally or figuratively)

1) to be bitter 1a) (Qal) to be bitter 1b) (Piel) 1b1) to show bitterness 1b2) to make bitter 1c) (Hiphil) to make bitter, embitter 1d) (Hithpalpel) 1d1) to embitter oneself 1d2) to be enraged 2) (TWOT) to be strong, strengthen

a primitive root; properly, to trickle (see מַר (H4752)); but used only as a denominative from מַר (H4751);