And God blessed them, saying:”Be fruitful, and multiply, and fill the waters in the seas, and let winged creatures multiply in the earth.” Gen 1:22
The primitive root
Strong’s H4390 מלא male, a primitive root meaning, “to fill, to be full.” The ancient pictographs are mem + lamed + aleph.
mem מ, ם = the water, thus chaos, mighty, blood
lamed ל = the shepherd’s staff, thus teach, yoke, to, bind
aleph א = the ox head, thus strength, power, leader
The story is of chaos (mem) brought into order (lamed) by leadership (aleph). So cognate words from this root include speaking a word, as individual words are brought into order to convey a message by strength of mind or will; branch, as they individually branch out in order from the tree through the agency of a strong root; firstfruits, as individual fruits are combined to convey the strongest of the harvest, and Lord, as one who is full of authority. So the sense of filling the earth is of bringing the earth’s chaos into order by increasing or becoming stronger, in it.