Stiff

[1] Not easily bent or turned. As opposed to a rigid object, a stiff object does not break when subjected to bending stress, and implies a certain degree of flexibility; a bridge, for example, is stiff, not rigid, and steel panels are inherently stiff; however, a particularly high degree of stiffness, e.g., when steel panels are shaped to a load-carrying structure, is sometimes referred to as rigid.
[2] A stiff ship is one which have a short period of roll and therefore will roll uncomfortably