allotropy

Từ điển Oxford Advanced Learner 8th

al·lot·ropy 7 BrE [əˈlɒtrəpi] NAmE [əˈlɑːtrəpi] noun uncountable (chemistry)
the existence of two or more ↑allotropes of a chemical element

Word Origin:
[allotropy] mid 19th cent.: from Greek allotropos ‘of another form’, from allo- ‘other’ + tropos ‘manner’ (from trepein ‘to turn’).