amphoteric
adjective
am·pho·ter·ic ˌam(p)-fə-ˈter-ik 
: partly one and partly the other
specifically : capable of reacting chemically either as an acid or as a base
Word History
Etymology
borrowed from German amphoterisch, from Greek amphóteros "either of two, (in plural) both" (derivative, with the suffix of ordering -teros, of ámphō "both") + -isch -ish — more at ambi-
First Known Use
1832, in the meaning defined above
Medical Definition
amphoteric
adjective
am·pho·ter·ic ˌam(p)-fə-ˈter-ik
: partly one and partly the other
specifically : capable of reacting chemically either as an acid or as a base