a system (including the thymus and bone marrow and lymphoid tissues) that protects the body from foreign substances and pathogenic organisms by producing the immune response | the fatty network of connective tissue that fills the cavities of bones |
| the choicest or most essential or most vital part of some idea or experience |
| large elongated squash with creamy to deep green skins |
| very tender and very nutritious tissue from marrowbones |
| any of various squash plants grown for their elongated fruit with smooth dark green skin and whitish flesh |