It is always interesting to consider where the title of plays, short stories or novels comes from. Often, the title is mentioned in the play and examining the context of where it is mentioned can be very revealing when we think about why an author or playwright has given his or her work the title that they have. Key to understanding Trifles is realising that Glaspell is presenting us with two completely different worlds--one of them male, the second female, and exposing the radical differences between them.
In this play we are presented with a murder scene and a group of men who are trying to find clues that might indicate who killed John Wright. Mrs. Peters and Mrs. Hale watch their menfolk engage in this task, but as they stay downstairs, ironically it is they who are able to use their knowledge of running a household and the day-to-day tasks that women have to do to find out who committed the murder. Yet, at the start of the play, this knowledge, which is shown to be so key, is dismissed by Mr. Hale as "trifles." Certainly not important enough for a man to bother about knowing. As Mrs. Peters talks about preserves, the men talk:
SHERIFF: Well, can you beat the woman! Held for murder and worryin' about her preserves.
COUNTY ATTORNEY: (setting his lips firmly) I guess before we're through she may have something more serious than preserves to worry about.
HALE: Well, women are used to worrying over trifles.
Note the dismissive tone in the way that the men talk as they are shown to underestimate the knowledge involved in the sphere of women. This is something that is repeated again and again in this masterful play as the men jokingly refer to various aspects of women's work and ironically highlight their lack of knowledge and their inability to solve the crime that the women manage to work out. The supposed "trifles" of a women's world are actually shown to be of vital importance.