Words have a lot of power. Certain words can immediately hurt someone's feelings. Other words can reassure. Some of the most dangerous words provide a false reassurance, and should never be used by a pilot. In a recent FAASTeam Safety Tip (faasafety.gov), Max Trescott, the 2008 National CFI of the year, warned pilots about the use of the word "probably." As he points out, human beings, and especially pilots, are generally optimistic. If you are using the word probably, "there's a good chance that you've overestimated the probability of success, as do the approximately 300 pilots a year who suffer fatal accidents."