Transgender 
-An umbrella term that may be used to describe people whose gender expression does not conform to cultural norms and/or whose gender identity is different from their sex assigned at birth.

Cis-Gender
-A person whose gender identity matches their gender assigned at birth. Often preferred over terms such as “biological” or “natal” man or woman.

Gender Expression
-This refers to an individual’s physical characteristics, behaviors, and presentation. This can include one’s appearance, dress, mannerisms, speech patterns, and social interactions that are linked, traditionally, to masculinity or femininity.

Gender Fluid/ Gender Queer
-Someone who embodies characteristics of multiple genders, or shifts in gender identity.

Gender Identity
-Our way of understanding our inner sense of being male, female, both, or neither. Sometimes clashes with the way other people view us physically.

Questioning
-The term is referring to people who are unsure or questioning their gender identity or sexual orientation.

Transgender
-A self-identity and some gender non-conforming people do not identify with this term.

These definitions are from Trans Bodies, Trans Selves, edited by Laura Erickson-Schroth, which is a great resource for learning more about the above terms.

Reference:
Erickson-Schroth, L. (2014). Trans bodies, trans selves: A resource for the transgender community.