THE TITLE "MUSICOLOGIST" is such a collection of dry syllables that it sounds, almost by definition, dull. But if ever there were need for proof to the contrary, ample evidence could be found in the sweeping career of Harold Spivacke, who died on Monday at 72. It was he who, as chief of the Library of Congress's music division for about a third of a century, presided over a monumental effort in the collecting, conserving, commissioning and making of music.

During those years, the music division became probably the world's largest music-research facility. Mr. Spivacke supervised acquisition of the large part books and pamphlets on the subject and 700,000 recordings - plus special projects like the library's folk music recordings.

But if Mr. Spivacke gave great service to scholarship by persuading the wealthy to entich the library's collection, he gave equal service to Washington audiences through arranging another bequest, the Whittall Foundation concerts. Since the 1930s the Budapest Quartet - and now the Juilliard Quarted - has played regular concerts on the library's five Strads in the Coolidge auditorium. These events became the centerpeice of a chamber-music series that made Washington, in this field, a major performing-arts center long before its cultural blossoming in other areas.

Mr. Spivacke's greatest legacy, though, is likely to be the dozens of workd commissioned under his direction through the Coolidge, Koussevitzky and McKim Foundation. If the most widely known of these works is Copland's haunting "Appalachian Spring," there are numerous compositions of comparable quality by virutally every major contemporary composer - from the gentle lyricism of a Britten to the fat-one modernism of a Stockhausen.

Mr. Spivacke was one of those rare persons who at an early age go right to the top of their professions, and are so superbly equipped that they simply stay stay there until retirement. Thus it was his good fortune, and ours, to have Mr. Spivacke at the helm for 35 years. In a letter written in a melancholy moment to Mr. Spivacke, the wife of Arnold Schoenberg, the musical revolutionary whose atonal works suffered the fate during his lifetime of being more talked about than performed, refers to the library as "the only institution that has not deserted us." That, Mr. Spivacke would have held, was exactly what the institution - and he - were there for. For three and a half decades, Mr. Spivacke accepted his high responsibility in the fullest sense of that term.