1. To confine or encircle with a band or bandage. 2. To join together with a band or ligature. 3. To combine or unite molecules by means of reactive groups, either in the molecules themselves or in a chemical added for that purpose; frequently used in relation to chemical bonds that may be fairly easily broken (noncovalent), as in the binding of a toxin with antitoxin, or a heavy metal with a chelating agent. 4. A close interpersonal relationship in which one person feels compelled to act in a certain way to obtain the approval of another.