identity
/aɪˈdentətɪ/noun
(pl. -ies)
1
- the fact of being who or what a person or thing is身份; 本体：
he knows the identity of the bombers
他知道投炸弹者的身份
mass noun she believes she is the victim of mistaken identity.她确信自己是被认错身份的受害者。
1.1
- the characteristics determining this（确定身份的）特征：
he wanted to develop a more distinctive Scottish Tory identity.
他想具有更为突出的苏格兰保守党人特征。
1.2
- as modifier(of an object) serving to establish who the holder, owner, or wearer is by bearing their name and often other details such as a signature or photograph（物件）能证明持有者身份的：
an identity card.
身份证。
2
- a close similarity or affinity同一性; 一致：
the initiative created an identity between the City and the governing elite.
这一倡议使伦敦城与执政精英之间达成了一致。
3
- Mathematics （亦作identity operation）a transformation that leaves an object unchanged【数】恒等运算。
3.1
- （亦作identity element）an element of a set which, if combined with another element by a specified binary operation, leaves that element unchanged单位元素, 幺元。
4
- Mathematics the equality of two expressions for all values of the quantities expressed by letters, or an equation expressing this, e.g. (x + 1)2 = x2 + 2x + 1【数】恒等（式）（如(x + 1)2 = x2 + 2x + 1）。
词源
late 16th cent. （in the sense 'quality of being identical'）： from late Latin identitas, from Latin idem 'same'.