echad, “one,” strong’s H259

The first occurrence.

And God called the light Day, and the darkness He called Night. And there was evening and there was morning, one day. Gen 1:5

The primitive root.

Strong’s H259, echad, an adjective meaning, “one, first, every;” from Strong’s H258 אחד achad, a primitive root meaning, “to unite.” The 3-letter root is aleph + chet + dalet.

aleph א = the ox head, thus strength, power, leader
chet ח = the wall, thus outside, divide, half
dalet ד = the door, thus enter, move, hang

The parable being told: To strongly (aleph) fence (chet) the door (dalet). When a man and his wife are one, the door is strongly fenced so that exiting (either the house or the relationship) is not an option.

THE ANCIENT HEBREW LEXICON | INDEX OF HEBREW ROOTS