The image at the heart of this root is standing in front of. Stand against someone and you get opposition, resistance, the preposition נֶגֶד, "against". But stand and lay something out before someone and you get the other branch: to tell, and from it the Passover Haggadah, the telling. Facing someone can mean confronting them or recounting to them; this root holds both. Even the electrical resistor (נַגָּד) is named for "standing against" the current. Every word here is verified against pealim, niqqud included.
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
This root has two distinct hif'il verbs: לְהַגִּיד is the everyday "to tell" (the נ assimilates, so the root letter vanishes from sight), while the rarer לְהַנְגִּיד keeps all three letters and means "to contrast". The hitpa'el לְהִתְנַגֵּד is the active "to resist", reflexive in form but oppositional in sense. Nif'al, pi'el and the pu'al-style passives are not lexicalized here.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.