The term "snuff" was respondent defined. The 1987 Field Representative's Manual defined snuff as, "a smokeless tobacco product that is either inhaled through the nostrils or placed in the mouth between the cheeks and gum or under the tongue. A common term for snuff use is "dipping." It add that this definition was for the interviewer's information only, and the term snuff should only be defined for the respondent if questioned. It also instructed interviewers to record, "DK Snuff" if the respondent reported they did not know what snuff was and to accept other brands of snuff as well as those given as examples.

The 1992 Manual mentions that using snuff includes sniffing it or just placing it in the mouth. This definition was not routinely shared with respondents.