osmiamic

from The Century Dictionary.

• Noting an acid obtained by decomposing its barium salt with dilute sulphuric acid. It forms a yellow solution in water, which if concentrated soon undergoes decomposition. Its formula is HNO₈O₃, and it probably contains the nitroso-group.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Chem.) Of, pertaining to, or designating, a nitrogenous acid of osmium, H2N2Os2O5, forming a well-known series of yellow salts.