The Pentomino-Dictionary
The pentominoes are often named after the letters of the Latin alphabet that they vaguely resemble.

Here are the few English words which can be written with these letters :

fifty, fill, fillip, filly, fin, Finn, finny, fit, fitful, fitfully, fitly, fix, fixity, fizz, fizzy, flint, flintily, flinty, flip, flit, flu, fluff, fluffy, fluty, flux, fly, fulfil, fulfill, full, fully, fun, funnily, funny, futility, fuzz, fuzzily, fuzzy
if, iffy, ill, illy, in, infinity, infix, influx, inly, inn, input, intuit, inulin, inutility, it, ivy
li, lift, lilliput, lilt, lily, linin, linn, lint, linty, liny, lip, lippy, lit, LP, luff, lull, lulu, lunt, luny, lupulin, lux, lynx
nifty, nil, nill, ninny, nip, nippy, nit, nitwit, nix, nu, null, nullify, nullity, nun, nut, nutty
pi, pill, pin, pint, pinup, piny, pip, pipit, pippin, pit, pitiful, pitifully, pity, piu, pixy, ply, PPI, puff, puffin, puffy, pul, puli, pull, pulp, pulpit, pulpy, pulvilli, pulvini, pun, punily, punt, punty, puny, pup, pupil, puppy, put, putt, putty, pyx
ti, tiff, tiffin, til, till, tilt, tin, tinily, tinnily, tinny, tint, tiny, tip, tipi, tit, titi, tittup, Tiu, tizzy, TNT, tuff, tuft, tufty, tui, tulip, tun, tunny, tup, Tupi, tut, tutti, tutty, tutu, tux, Twi, twilit, twill, twin, twiny, twit, twixt, typify, typy
unfit, unfitly, unfix, unify, unit, unity, unpin, until, unzip, up, uplift, uppity, uptilt, ut, utility
vilify, vill, villi, viny, vinyl, VIP, vivify, vt
wilful,wilily,will,willful,willfully,willy,wilt,wily,win,winy,wit,wittily,witty,wiz
xi
yill,yin,yip
zip,zippy,Zulu,Zuni

Katrijn Cierkens make a real "TULIP"