A man of relentless self-discipline, he made clear to lawmakers in Boston and colleagues in business that even in matters of vocabulary, he “held himself to a high standard of behavior,” said Geoffrey Rehnert, a former executive at Bain Capital, the firm Mr. Romney started in the 1980s. Mr. Romney’s father, George, whom he idolized, shared the same style of refined and restrained speech…

Mr. Romney does have his own distinctly G-rated arsenal of angry expressions — “Good grief,” “flippin’,” “good heavens” and even the occasional “crap.”

Perhaps the most intriguing of these is “grunt.” Most people just grunt. Mr. Romney, however, talks about grunting. “Grunt” he says, onomatopoetically, when annoyed with a last-minute change in his campaign schedule.

Many of Mr. Romney’s verbal habits can sound like those of a hyper-literate graduate student who never left school. (In college, he majored in English.) He favors the gentlemanly qualifier “if you will,” which he invoked three times during a recent speech in New Hampshire.