clam

Safe from harm. Likened to a clam closing its shell to protect itself. All of the doors and windows are locked. Don't worry, we'll be close as a clam in here.

Very joyful and content. Clams are dug at low tide, so a clam at high tide would be able to remain uncaught. Look at your sister out there! She's happy as a clam at high tide now that she's back in the starting lineup again. I know I'll be happy as a clam at high tide once I get this stupid cast off my leg.

to say nothing. (Closing one's mouth in the way that a clam closes up.) The minute they got him in for questioning, he clammed up. You'll clam up if you know what's good for you.

contented; very happy. (*Also: as ~.) I've been as happy as a clam since I moved to the country. I don't need much. Just somewhere to live, some work to do, and a TV to watch, and I'm happy as a clam at high tide. Matthew was happy as a lark throughout his whole vacation. Bob was happy as can be when he won the lottery.

to refuse to talk or answer Every time I think he's going to tell me what's bothering him, he just clams up.

very happy I am happy as a clam living all by myself in this little house by the sea.

to be very happy and to have no worries We married nine days after we met, and three years on we're happy as Larry. Since he's been at college he's as happy as a clam.

to suddenly stop talking and to refuse to say any more When I asked him about his trip to Korea, he shut up like a clam.

Refuse to talk or respond, as in Whenever she asks her teenager about his activities, he clams up. This term alludes to the tightly closed valves of a live clam. [Slang; early 1900s]

Also, happy as a lark; happy as a clam (at high tide). Extremely glad, delighted, very cheerful, as in He was happy as the day is long, or When she heard the news she was happy as a lark, or Once I got the test results I was happy as a clam at high tide. The first of these similes dates from the late 1700s. The second alludes to the lark's beautiful, seemingly very happy, song. The third, from the early 1800s, alludes to the fact that clams can only be dug at low tide and therefore are safe at high tide; it is often shortened to happy as a clam.