Answer:

steeliest

Answer	Crossword Clue
STEELIEST	With the most nerve
STEELIEST	Most unemotional
STEELIEST	Hardest.

STEELIEST	Most unyielding.
STEELIEST	Hardest and strongest
STEELIEST	Superlatively strong

Crossword

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