Here the term bull evidently pertains to tasks that are pointless in that they have nothing much to do with the primary intent or justifying purpose of the enterprise which requires them. Spit-and-polish and red tape do not genuinely contribute, it is presumed, to the “real” purposes of military personnel or government officials, even though they are imposed by agencies or agents that purport to be conscientiously devoted to the pursuit of those purposes. Thus the “unnecessary routine tasks or ceremonial” that constitute bull are disconnected from the legitimating motives of the activity upon which they intrude, just as the things people say in bull sessions are disconnected from their settled beliefs, and as bullshit is disconnected from a concern with the truth.
The term bull is also employed, in a rather more widespread and familiar usage, as a somewhat less coarse equivalent of bullshit. In an entry for bull as so used, the OED suggests the following as definitive: “trivial, insincere, or untruthful talk or writing; nonsense.” Now it does not seem distinctive of bull either that it must be deficient in meaning or that it is necessarily unimportant; so “nonsense” and “trivial,” even apart from their vagueness, seem to be on the wrong track. The focus of “insincere, or untruthful” is better, but it needs to be sharpened. The entry at hand also provides the following two definitions: