The following terms and definitions were first published by me in my Ph.D. dissertation on first blind dates, chemistry, and factors in first time intercourse with a new partner. They are copyrighted, and may be used only with attribution to Robert Berend, Ph.D. Thank you for respecting my work and creativity.
Chemistry - Chemistry is defined here a s a feeling of affiliation, bonding and/or comfort, which is sometimes present in the first few (often less than 15) minutes of meeting someone new. Chemistry can persist for years in friendship or a sexual relationship, but as it pertains to first dates and meeting strangers, it refers to a rather immediate feeling of rapport, comfort and liking. Sexual interest may be present but it is not required. It may also be used to define a strong sexual attraction, sometimes without the presence of the feelings of compatibility, comfort, rapport, etc. In the initial first meetings or dates of a relationship, people in our culture often (but not always) seek this feeling as a precursor to further friendship or sexual intimacy. (Definition by Robert Berend.)
Bilateral eureka - This is the Holy Grail of what, it seems, many daters are looking for. It's important that some "energy/feeling/connection" or "chemistry" be present to develop rapport with a stranger. Habitual daters who are expecting to be swept off their feet with the next date may be missing this Eureka feeling by having unrealistic expectations. Many people seem to know in the first 15 minutes or so of a first meeting whether or not there is a future to the relationship, but it is hard to get to know a person that quickly. It's difficult for one person to be enchanted with another person, and substantially more difficult for two strangers to both feel "Eureka" when they meet the next stranger. (Definition by Robert Berend.)
Date - A date is defined here a s a romantic meeting between two individuals for the purpose of getting acquainted, to discover the beliefs, mannerisms, looks, and facets of the other person. Whereas a blind date deals with two people who have never been face to face, a date is a social vehicle for exploring a possible friendship and relationship between two people who do not know each other well. Going out with a co-worker, meeting someone coincidentally in public, or getting together with an acquaintance with the purpose of learning more about him or her is a date. Dating is a vehicle by which two individuals can come together to interact and to find out more about one another (Christopher & Frandsem, 1990, p. 89). Dating is a process for meeting and getting to know a person. (Definition by Robert Berend.)
One night stand - This term connotes a one time only sexual relationship. It generally means sexual intercourse. There is no continuation of the relationship between the parties, and this may be expressly made clear from the start, or might be the result for whatever reason. It may be mutually consented to by both from the outset, or not. This is also known as no strings attached (NSA) or a hookup type of relationship. (Definition by Robert Berend.)
Placeholder/placeholding relationship - This term identifies a relationship where one or both parties know the other is not satisfying their "wish-list." Due to some needs or wants (e.g. loneliness, sex drive, extraversion, frustration with lack of dating, no better option available) there is an ongoing relationship for the time being, but at least one person knows this will not be a permanent relationship, but they are getting some type of value from staying together. This could be sex, status, money or other tangible rewards, or just someone to relieve boredom or loneliness. (Definition by Robert Berend.)