This is the 4162nd most frequent Arabic word.
ضيف
Guest.
Here, 'ضيف' means 'guest', someone who visits a place.
جاء ضيف إلى منزلنا مساء أمس.
A guest came to our house yesterday evening.
In this context, 'ضيف' metaphorically means 'host', referring to an entity that facilitates a process.
قامت الشجرة بدور ضيف في تشبيع النبات بالماء.
The tree served as a host in saturating the plant with water.
Here, 'ضيف' is used as a verb meaning 'to add', derived from the same root.