rock hard

adj 0.755

hard-nosed

adj 0.739

hard

adj 0.705

tough

adj 0.665

hard put

adj 0.650

hardball

adj 0.649

hard-set

adj 0.648

iron-hearted

adj 0.647

stiff as a poker

adj 0.629

made of sterner stuff

adj 0.622

adamantine

adj 0.622

diehard

adj 0.620

hardy

adj 0.615

hard-boiled

adj 0.612

strong as a horse

adj 0.606

ironclad

adj 0.605

hard-and-fast

adj 0.605

nailed

adj 0.603

hardheaded

adj 0.597

hardened

adj 0.595

hardline

adj 0.595

stubborn as a mule

adj 0.593

hard-featured

adj 0.589

hardhearted

adj 0.587

rock-ribbed

adj 0.583

stone cold

adj 0.578

hardscrabble

adj 0.574

hard-charging

adj 0.571

bulletproof

adj 0.570

unyielding

adj 0.569

cold as ice

adj 0.569

stiff as a board

adj 0.568

stiff

adj 0.568

bold as brass

adj 0.566

dry as a bone

adj 0.565

adamant

adj 0.563

dead set

adj 0.562

sharp as a tack

adj 0.561

unflinching

adj 0.560

flinty

adj 0.559

steady as a rock

adj 0.557

keen as mustard

adj 0.556

take-no-prisoners

adj 0.551

unbreakable

adj 0.551

hardenable

adj 0.551

hard hit

adj 0.548

headstrong

adj 0.548

harsh

adj 0.547

bombproof

adj 0.544

steely

adj 0.544

stonelike

adj 0.543

indurate

adj 0.541

rugged

adj 0.541

hardwood

adj 0.538

leather-hard

adj 0.537

bullheaded

adj 0.537

industrial strength

adj 0.536

sturdy

adj 0.536

tenacious

adj 0.535

ruthless

adj 0.534

fierce

adj 0.533

nuts

adj 0.533

rigid

adj 0.533

cutthroat

adj 0.532

stone deaf

adj 0.531

strong-willed

adj 0.531

hobnailed

adj 0.529

rigorous

adj 0.529

hell-bent

adj 0.528

unforgiving

adj 0.527

bare knuckle

adj 0.526

callused

adj 0.526

hardpressed

adj 0.526

staunch

adj 0.525

bone

adj 0.525

indurated

adj 0.524

mettle

adj 0.524

stony-faced

adj 0.523

strong

adj 0.523

uncompromising

adj 0.522

dogged

adj 0.520

scared stiff

adj 0.519

ironbound

adj 0.518

unhardened

adj 0.517

indestructible

adj 0.517

no holds barred

adj 0.516

callous

adj 0.515

stubborn

adj 0.515

difficult

adj 0.515

case hardened

adj 0.514

unbending

adj 0.513

unrelenting

adj 0.512

arduous

adj 0.512

implacable

adj 0.511

unshakable

adj 0.511

steel

adj 0.509

good as gold

adj 0.508

stringent

adj 0.507

stalwart

adj 0.507

impregnable

adj 0.506