There are 9 13-letter words that start with 'lu'.
| lucrativeness | ludicrousness |
| luminescences | lumpishnesses |
| luncheonettes | lustfulnesses |
| luteinization | luteotrophins |
| luxuriousness | |
Note: These 9 13-letter words that start with 'lu' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with lun, lum, lus, luc, lut, lur, lub, lug, lux, lul, lup, luf, lud, luk, lue, lua, luv.
3-letter words start with 'lu' (4)