Letters that make periodic movement
o, d, e, n, p, c, m, r, t, i, v are letters that make 'periodic movement'
Words within periodic movement
ER, OD, pe, period, OV, NT, men, IC, em, en, RI, periodic, ic, move, movement, Rio, ME, MO, Io, peri, Er, Mo, mo are words within 'periodic movement'