Many in the transgender community use the term "trans," and you might be guessing at what it means. Below is a definition that I wrote for "Sexuality: The Essential Glossary," Oxford University Press. Note that not everyone agrees that my definition is correct.
Trans - describing persons whose gender does not conform to norms, e.g., a trans man, the trans community. This is taken from the prefix used with several words used to describe gender variance, i.e., transvestite, transsexual, transgender. It is sometimes used as a less-controversial synonym of "transgender," in that "trans" references, but does not specify, transvestite, transsexual and transgender people, as well as other gender variances. This makes it a fluid descriptor which is a broad, yet specific reference depending on context, which avoids the problems of the term transgender.
"Transgender" is problematic on several grounds. While the term "transgenderist" was originally created to contrast with the terms transvestite and transsexual, referring to those who whose live in a sex role different from their anatomical sex, but who do not desire sex reassignment surgery (Holly 1991:31), "transgender" has been extended by some to refer to all gender-variant people. Some criticize this extension on the grounds that it creates a problematic category which unites persons of differing, and perhaps conflicting political interests (Namaste 2000). Moreover, the understanding of "transgender" as implying that gender is a social or psychological construct can ironically result in a solidification of the binary nature of "biological" sex (Valentine 2001:2). Further complicating the picture, "transgender" is a "discourse in motion," a term controversial even among those whom it purports to describe, and is primarily a white middle class US and UK identifier, reproducing social hierarchies of race, class and gender. (Ibid:7-8). For these reasons, many people prefer to use the term “trans.”
The dispute surrounding the term transgender, leading to a preference for trans, has been described as follows: "Who knows what to call transpeople these days? The dominant discourse in the transcommunity is at best a moving target. . . . Transgender began as an umbrella term, one defined by its inclusions rather than its boundaries, coined to embrace anyone who was (in Kate Bornstein's felicitous phrase) 'transgressively gendered.' . . . Increasingly, the term has hardened to become an identity rather than a descriptor. . . . But at some point such efforts simply extend the linguistic fiction that real identities (however inclusive) actually exist prior to the political systems that create and require them." (Wilchins 1997:15-17)