女友指浪漫或性關係(romantic/sexual relationship)中相對穩定(regular)的女性夥伴，但通常不屬於長期承諾性的關係(long-term committed relationship)，這種情況需要用妻子(wife)或愛侶(partner)的說法。
1. Girlfriend也可以簡稱girl
特別隨意的場合可以用gf或GF，如短信(texting)或網聊(internet chat)。
eg: Have you been seeing a guy pretty steadily and would like to know if he wants you to be his girlfriend?
2. 非婚關係中，口語通常可稱女方為significant other或SO
這個詞不突出性別，只強調親密關係，所以也可用於男方。類似漢語的‘另一半兒’、‘那口子’、‘他那位’等，但不透露或假設婚姻狀態或性取向，用於故意模糊以避免冒犯別人。
eg: Anyone NOT having their Significant Other in the Delivery Room?
3. Life partner通常相當於‘終身伴侶’
但與漢語不同的是它也可以指親密的終身夥伴，無論同性還是異性。Partner也可以指life partner。
eg: I feel more optimistic being in this relationship. We decided we are going to be life partners.
4. Soulmate或soul mate可以指女友或妻子
也可以指未必有親密關係的精神伴侶，有一定的神秘或宗教意味。另外，mate也可以指女友。這幾個詞不區分性別。
eg: So did "God" give attractive people a much higher chance of meeting their soulmate?
5. Fianc岢e指訂婚女友
相對概念是fianc岢，及訂婚男友。
eg: A 45-year-old man and his fianc岢e were celebrating a family holiday in their apartment. Out of the blue the man thought that his girlfriend was taking the form of a hideous monster from a horror movie.
6. 有一些詞是男女通用的，如true love、date、steady、darling、love、lover、paramour、squeeze等。
7. 還有其他一些詞可以指女友，如companion、sweetheart、heartthrob、babe等。
8. 如果是已婚男人的情人，通常用mistress
eg: Picasso’s painting of his mistress will go under the hammer at London
9. Lady friend是個故意模棱兩可的用語
指關係不到girlfriend的程度，但卻好于friend；沒有mistress或lover那種明顯的性意味。通常作為委婉語(euphemism)使用，或者在情況不明的情況下作為一種保守的提法。Lady friend也用於指女方明顯大於男方的情侶關係。
eg: A millionaire took his lady friend to dinner. He told her he had eaten in the finest restaurants in the world and assured her this place served the best。
10. girl friend或female friend
沒有浪漫關係(non-romantic)或性關係的(non-sexual)女性朋友可用girl friend或female friend一詞。Girl friend和girlfriend也有所不同，前者可用於指一般女性朋友。
eg: The fine line between girl friends and girlfriends lies in sexual attraction and flirting.
文章來源：滬江英語