thallic

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of, relating to, or containing thallium, especially with valence 3.

from The Century Dictionary.

• In chem., of, pertaining to, or containing thallium: as, thallic acid.

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

• adjective (Chem.) Of or pertaining to thallium; derived from, or containing, thallium; specifically, designating those compounds in which the element has a higher valence as contrasted with the thallous compounds.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective inorganic chemistry Pertaining to or containing the element thallium, especially with valence 3.
• adjective Pertaining to a thallus.