Answer:

soapiest

Answer	Crossword Clue
SOAPIEST	Having the most lather
SOAPIEST	Most slippery, perhaps
SOAPIEST	Most sudsy

SOAPIEST	Suds-filled
SOAPIEST	With the most lather

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.