affinity

affinity
(pl. -ies)

a spontaneous or natural liking or sympathy for someone or something
本性爱好，同情心
he had a special affinity with horses.
他对马有天生的喜爱。
■a similarity of characteristics suggesting a relationship, especially a resemblance in structure between animals, plants, or languages
（尤指动物、植物、语言之间结构的）类同，相似性
a semantic affinity between two words.
■[mass noun]relationship, especially by marriage as opposed to blood ties
（与血缘关系相对的）姻亲关系
(chiefly Biochemistry)the degree to which a substance tends to combine with another
(主生化)亲和力，亲和性

语源

Middle English (in the sense 'relationship by marriage'): via Old French from Latin affinitas, from affinis 'related' (literally 'bordering on'), from ad- 'to' + finis 'border'