In this pit, a viscous secretion is exuded, entering the groove and hardening gradually upon contact with sea water.

If left alone, plaque buildup also gradually hardens, creating tartar or calculus on your teeth.

Even when separated from the bush, the loops retained their potency for several days, gradually hardening in place.

When mixed these yield a dough-like cement that gradually hardens.

In the early to mid seventeenth century, however, the ruling kandas gradually hardened into permanent divisions.

The White House efforts represent a response to a Washington reality: with or without the help of Bush aides, perceptions of the new Administration are gradually hardening.

You get that "Gradually hardening chocolate" - that's it.

As the nipple gradually hardened beneath my circling finger she laughed, an abrupt, angry little laugh, and tossed off the remainder of her brandy.

Traditional oil paints require an oil that gradually hardens, forming a stable, impermeable film.

The sutures gradually harden by a process called ossification, which firmly joins the skull bones together.