Root ر ص د(r S d) has 5 unique word forms and appears 6 times in the Quran.

English gloss Watch, Observe, Lie in Wait, Observatory

Word Translation Occurrences
رَصَدٗا a guard, a guard 2
رَّصَدٗا waiting, waiting 2
لَبِٱلۡمِرۡصَادِ (is) surely Ever Watchful, (is) surely Ever Watchful 2
مِرۡصَادٗا lying in wait, lying in wait 2
مَرۡصَدٖۚ place of ambush, place of ambush 2
وَإِرۡصَادٗا and (as) a station, and (as) a station 2