One image sits under all of these: things blending into one another. Blend the day into the night and you get evening (עֶרֶב) and the west (מַעֲרָב) where the sun mixes into the horizon. Blend yourself into someone else's affair and you get to interfere or to bet (לְהִתְעָרֵב). Bind your fate to another's debt and you get a guarantee (עַרְבוּת) and the deep idea of mutual responsibility. Even pleasantness, a taste that agrees with you, that mingles well, comes from here (עָרֵב). The three letters never change; the world they describe is one of boundaries dissolving. Every word below 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.
There is also a stative pa'al עָרֵב "to be pleasant", but Hebrew normally meets that sense as an adjective (see group ④), so we list the adjective rather than a separate verb row. Notice the pa'al/hitpa'el jump: pour the mixing idea into the reflexive mould and "mix oneself in" becomes both interfering and betting, two people throwing their stakes into one pot. The passives nif'al, pu'al and huf'al are not lexicalized as headwords 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.