toughen

As a verb toughen

is to make tough.

As a noun harden is

.

As verbs the difference between toughen and hardened

is that toughen is to make tough while hardened is (harden).

As an adjective hardened is

unfeeling or lacking emotion due to experience; callous.

In transitive terms the difference between firm and toughen

is that firm is to make compact or resistant to pressure; solidify while toughen is to make tough.

In intransitive terms the difference between firm and toughen

is that firm is Aust. To shorten (of betting odds) while toughen is to become tough.

As a noun firm

is a business partnership; the name under which it trades.

As an adjective firm

is steadfast, secure, hard (in position.

As verbs the difference between toughen and toughened

is that toughen is to make tough while toughened is past tense of toughen.

In lang=en terms the difference between toughen and stiffen

is that toughen is to become tough while stiffen is to become stiff.

As verbs the difference between toughen and stiffen

is that toughen is to make tough while stiffen is to make stiff.

In lang=en terms the difference between inure and toughen

is that inure is to cause (someone) to become accustomed (to something); to habituate while toughen is to become tough.

As verbs the difference between inure and toughen

is that inure is to cause (someone) to become accustomed (to something); to habituate while toughen is to make tough.

As an adjective tougher

is (tough).

As a verb toughen is

to make tough.

In transitive terms the difference between roughen and toughen

is that roughen is to make rough while toughen is to make tough.

In intransitive terms the difference between roughen and toughen

is that roughen is to become rough while toughen is to become tough.

As verbs the difference between toughen and toughed

is that toughen is to make tough while toughed is (tough).

As a noun taxonomy

is the science or the technique used to make a classification.

As a verb toughen is

to make tough.