Basic Sexuality Definitions
Heterosexual - straight, likes the opposite gender
Homosexual - gay, likes the same gender
Bisexual - likes both genders, tends to lean towards one though
Pansexual - doesn't care about gender, focuses more on personality
Asexual - no sexual desire. Are still able to have romantic feelings and form relationships
Basic Gender Definitions
Male/Female - self explanatory. Please don't be a wise guy and ask what this means, you will be banned
Agender - identifies as neither male or female despite having genitalia for one or the other.
Transgender - in transition or has transitioned from male to female or vice versa.
Hermaphrodite (gender) - person who has both male and female genitalia. Despite having both, commonly only one system is fully functional, however there are occurrences of both sets being fully operational. Also typically a gender is still assigned (hence the gender part in the name)
More may be added as needed.