The present article discusses the use of the term šuġl and related terms in Arabic grammatical tradition. The lion’s share is dedicated to Sībawayhi’s Kitāb; it is shown that it is used there in three related senses: priority (i.e. an operator assigns case to some constituent, hence it is said to be ‘occupied’ by that constituent, and correspondingly ‘diverted’ from another constituent, which renders it free to be operated on by some other operator); satisfaction of an operator’s requirement to syntactically effect some constituent; and the verb-subject relationship. Among later grammarians most occurrences of the term conform with its usages in the Kitāb, although the extent to which it is used significantly varies among authors. Several ninth/tenth-century grammarians also use it in a fashion which we dub ‘reverse’, as it is applied not to an operator but rather to the constituent that is operated on.