| an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle. |
| an extraordinary or unusual thing, person, or event; an exceptional example or instance. |
| Mendeleev (měn'də-lā'əf) Pronunciation Key
Russian chemist who devised the periodic table, which shows the relationships between the chemical elements. He first published the Table in 1869 and continued to refine it over the next 20 years. |