STIFFEN, verb transitive

1. To make stiff; to make less pliant or flexible; as, to stiffen cloth with starch.

He stiffened his neck and hardened his heart from turning to the Lord God of Israel. 2 Chronicles 36:13.

STIFFEN the sinews; summon up the blood.

2. To make torpid; as stiffening grief.

3. To inspissate; to make more thick or viscous; as, to stiffen paste.

STIFFEN, verb intransitive

1. To become stiff; to become more rigid or less flexible.

--Like bristles rose my stiffning hair.

2. To become more thick, or less soft; to be inspissated; to approach to hardness; as, melted substances stiffen as they cool.

The tender soil then stiffning by degrees--

3. To become less susceptible of impression; to become less susceptible of impression; to become less tender or yielding; to grow more obstinate.

Some souls, we see, grow hard and stiffen with adversity.