harden your heart

harden | American Dictionary

harden
verb[ I/T ]
us/ˈhɑr·dən/

hardenverb[I/T] (MAKE SEVERE)

to make or become stronger or more severe:
[ I ]As the war progressed, attitudes on both sides hardened.

hardenverb[I/T] (BECOME SOLID)

to become firm or solid, or to cause something to become firm or solid:
[ I ]In a few hours the cement will harden.

harden | Business English

harden
verb[ I ]
 FINANCE, STOCK MARKET UKuk /ˈhɑːdən/us
if prices or share prices harden, they increase:
If the oil price hardens this week and remains high, there will be some effect on fuel prices by the end of this week.
The pharmaceuticals company hardened 33p at £26.07 on speculation of predatory interest from a Swiss firm.

Examples of harden

harden
An ultraviolet laser "paints" the object as a series of horizontal layers, exposing the liquid in the tank and hardening it.
The real social problem becomes identified then not as the criminal simpliciter but as the ' hardened ' or ' real ' criminal.
All plants were hardened off in direct sunlight 24 h prior to use.
Green oak is extremely durable and hardens over time while the cedar is soft with a surface which can be scored with a finger nail.
The hardening relation identifies the subprocesses of a process that may participate in a computation step.
Robots could be hardened to withstand these conditions and could even be considered to be disposable if they became too contaminated.
As theological divides hardened in the second half of the sixteenth century, it became even more difficult to occupy a middle ground between the confessions.
Low-temperature plastic deformation of the veins, without significant recovery, will also result in work hardening leading ultimately to fracture.
With the application of ultraviolet light, the epoxy cures to its fully hardened state with no mixing or additional mess.
During their earthly lives it is hardened in error.
After ecdysis the pupa was pale greenish, but it rapidly hardened and darkened to brown with traces of green coloration under the wings.
Initially it is rather soft, moist and fibrous, but it hardens and dries out with time.
All plants were hardened off outdoors in direct sunlight 24 h prior to use.
Alternatively, people hardened by war or personal crisis can at times appear 'numbed' or in shock.
Meanwhile, the soil may be drying, hardening, crusting and heating up.
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These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors.