tutren is a body-part word, used almost exclusively in DeS tutren and 'uS tutren. 'I', obviously, has its own word; volchaH tutren is okay, but it's likely to be used for rhetorical purposes or else if making a comparison between it and the other tutrenDu'. It's not just a "pit"; a tutren is associated with a joint. Maltz wasn't aware of other places on the body it might be used. In non-body contexts, it's often used when talking about a hinge or the angle between a door and a wall (when the door is open); in these cases, the plural is formed with -mey. Otherwise, in non-body contexts, it can be used, but it's likely to be used metaphorically.

DeS tutren can be glossed "elbow pit"; 'uS tutren can be glossed "knee pit" or "hollow of the knee." They can also be glossed "cubital fossa" and "popliteal fossa" if that would be useful or helpful. Or any other description you might think of!

When context is clear, tutren can be used by itself, but it's usually heard in the full N-N construction (DeS tutren, 'uS tutren).