be at loggerheads

To be in conflict. A "logger" is a 16th-century term for a block of wood, so a "loggerhead" is a blockhead or fool. They are at loggerheads over the best way to lead the committee. I've been at loggerheads with the neighbors all summer because of their obnoxious dogs. You two are still at loggerheads? Come on, can't you make up already?

To disagree, dispute, or quarrel. A logger was a heavy wooden block, and one meaning of “loggerhead” is “blockhead,” a stupid person or dolt. Possibly this meaning led to the phrase “at loggerheads,” with the idea that only dolts would engage in a quarrel. Shakespeare used the word as an adjective in The Taming of the Shrew (4.1): “You loggerheaded and unpolish’d grooms.” The full current expression appeared in the late seventeenth century.