Using all letters

                                                                           speechlessly

                                                                          The other words:

                                                                               cells

                                                                              cesses

                                                                               cheep

                                                                              cheeps

                                                                              cheese

                                                                              cheeses

                                                                              cheesy

                                                                               chess

                                                                              chesses

                                                                               clepe

                                                                               cycle

                                                                              cycles

                                                                              leches

                                                                               leech

                                                                              leeches

                                                                               lycee

                                                                              lycees

                                                                              lychee

                                                                              lychees

                                                                               psych

                                                                              psyche

                                                                              psyches

                                                                              psychs

                                                                              schlep

                                                                              schlepp

                                                                             schlepps

                                                                              schleps

                                                                               specs

                                                                              speech

                                                                             speeches

                                                                            speechless