Letters that make unreplaceable
a, b, e, l, n, p, c, r, u are letters that make 'unreplaceable'
Words within unreplaceable
lace, rep, AB, ab, re, la, ACE, UN, AC, replace, Ea, able, placeable, replaceable, ace, CE, place, LA, Re, LE, Ac, Ce, La, lac, Ab are words within 'unreplaceable'