Letters that make inter-group communication
a, o, e, g, n, p, c, m, r, t, i, u are letters that make 'inter-group communication'
Words within inter-group communication
ER, communication, ti, te, NT, UN, IC, mu, at, inter, Ro, mm, up, on, ic, in, group, cat, CAT, CA, CO, IN, cation, Io, ion, At, Ca, Co, Er, In, Ni, Te, Ti are words within 'inter-group communication'