​ADHESION (from Lat. adhaerere, to adhere), the process of adhering or clinging to anything. In a figurative sense, adhesion (like "adherent”) is used of any attachment to a party or movement; but the word is also employed technically in psychology, pathology and botany. In psychology Bain and others use it of association of ideas and action; in pathology an adhesion is an abnormal union of surfaces; and in botany "adhesion” is used of dissimilar parts, e.g. in floral whorls, in opposition to "cohesion,” which applies to similar parts, e.g. of the same whorl.