The noun relation has 6 senses (first 2 from tagged texts)
1. (27) relation -- (an abstraction belonging to or characteristic of two entities or parts together)
2. (2) sexual intercourse, intercourse, sex act, copulation, coitus, coition, sexual congress, congress, sexual relation, relation, carnal knowledge -- (the act of sexual procreation between a man and a woman; the man's penis is inserted into the woman's vagina and excited until orgasm and ejaculation occur)
3. relative, relation -- (a person related by blood or marriage; "police are searching for relatives of the deceased"; "he has distant relations back in New Jersey")
4. relation, telling, recounting -- (an act of narration; "he was the hero according to his own relation"; "his endless recounting of the incident eventually became unbearable")
5. relation back, relation -- ((law) the principle that an act done at a later time is deemed by law to have occurred at an earlier time; "his attorney argued for the relation back of the amended complaint to the time the initial complaint was filed")
6. relation -- ((usually plural) mutual dealings or connections among persons or groups; "international relations")