a modal quality or attribute; a form

the classification of logical propositions according to the possibility, impossibility, contingency, or necessity of their content

formal a method or procedure

Would it be possible for Matthew to call in at the office, at any time that was convenient to him, so that the modalities of the transfer could be discussed? Modalities was an expensive word, … not a word one would catch a lesser firm of lawyers bandying about — Alexander McCall Smith