The word 'stiffen' is correct and usable in written English.
It can be used as a verb to mean "to become rigid or resistant to movement, change, or yielding" or "to make or become harder or stronger". Example sentence: "The crowd's silence stiffened as the speech went on."
Thatcher told MacGregor in March 1984, according to the documents: "It was essential to stiffen the resolve of chief constables to ensure that they fulfilled their duty to uphold the law".
Were Major John Howard alive today, he would no doubt stiffen his ageing back, drop his walking stick and stand to attention in front of a glass museum case containing his commanding officer's uniform, to give a brisk salute.
Although Wilson is credited with not having sent troops to Vietnam, Healey hints that he had to stiffen Wilson's resolve.
They grow cold, their skin droops, their hands stiffen.
In Iraq, special forces might be allowed out of their bases to help spot targets for air attack, and to stiffen Iraqi units.
But, says a western diplomat, "the prospects of meaningful discussions at this stage are very, very poor".Fears of a backlashIt is unclear how much political pressure Mrs Kumaratunga will face to stiffen her line against the Tigers.
Communing with history is another way to stiffen the laxity of a vacation: famous buildings, battlefields and landmarks are popular and lucrative draws.
But the biggest challenge for many politicians will be confronting the enormously powerful teachers' unions.Parents and taxpayers should stiffen the politicians' spines.
Perhaps it was the frantic telephone calls he made to stiffen the spines of "blue dog" Democrats who represent Republican states in the South and are coming under pressure from their conservative constituents.Whatever the reason, the Democrats seem to be giving Mr Gore the support he needs.
He wants to make it harder for multinational firms to shift income to subsidiaries in low-tax countries, stiffen the rules on the credits American firms can claim for the foreign taxes they pay, and limit how much companies can defer tax payments on their foreign earnings.
Republicans and some Democrats in Congress have long worried that Mr Obama might strike a weak deal with Iran, and drafted bills that sought to stiffen the president's spine by setting out sanctions that could either be added or reimposed if Iran backslides.
