| diamond wedding |
a sixtieth or seventy-fifth wedding anniversary. |
| eightieth |
indicating rank or position between seventy-ninth and eighty-first. [2/3 definitions] |
| gold |
a precious yellow metal chemical element that has seventy-nine protons in each nucleus, that occurs in pure form as a very dense, lustrous, highly malleable solid, and that is often mixed with other metals to make it harder and stronger. (symbol: Au) [1/11 definitions] |
| hafnium |
a chemical element that has seventy-two protons in each nucleus and that occurs as a tetravalent metal often found in combination with zirconium, used in pure form for applications such as nuclear reactor control rods because it absorbs neutrons well. (symbol: Hf) |
| Halley's Comet |
a comet, last seen in 1986, that returns every seventy-six years. |
| iridium |
a chemical element that has seventy-seven protons in each nucleus and that occurs as a lustrous yellowish white, extremely hard, dense, and corrosion-resistant metal, used as a hardening alloy, esp. with precious metals. (symbol: Ir) |
| kana |
either of two Japanese syllabic scripts, katakana and hiragana, consisting of seventy-one characters each. (Cf. kanji.) [1/2 definitions] |
| king-size |
of a bed, about seventy-eight by eighty inches. [1/2 definitions] |
| lanthanide series |
a series of chemical elements having from fifty-seven to seventy-one protons in each nucleus; rare-earth elements. |
| lutetium |
a metal chemical element of the rare-earth group that has seventy-one protons in each nucleus. (symbol: Lu) |
| osmium |
a chemical element that has seventy-six protons in each nucleus and that occurs as an octavalent ion or in pure form as an extremely hard, dense, brittle bluish metal solid used as a catalyst and esp. in alloys and in electron microscopy because of its extremely high density. (symbol: Os) |
| platinum |
a chemical element that has seventy-eight protons in each nucleus and that occurs in pure form as a dense, highly malleable, lustrous silvery white solid metal, used as a catalyst, in a variety of alloys, and in making jewelry. (symbol: Pt) [1/2 definitions] |
| rare-earth metal |
any of the series of chemical elements, all metals, that have from fifty-seven to seventy-one protons per atom; lanthanide series. |
| rhenium |
a chemical element that has seventy-five protons in each nucleus and that occurs naturally only in compounds, but that can be isolated as a very dense metal, used esp. for electrical contacts and other high-temperature applications, and as a catalyst. (symbol: Re) |
| septuagenarian |
one who is seventy years old or between seventy and eighty years old. |
| seventieth |
indicating rank or position between sixty-ninth and seventy-first. [3 definitions] |
| seventy |
(pl.) the period in one's life from age seventy through age seventy-nine. [2/5 definitions] |
| sexagenarian |
being, of, or concerning one who is between the ages of sixty and seventy. [2 definitions] |
| tantalum |
a chemical element that has seventy-three protons in each nucleus and that occurs, usu. together with niobium, as a hard, corrosion-resistant gray solid metal with a very high melting point, used esp. in various instruments and equipment. (symbol: Ta) |
| tarot |
(sometimes cap.) any of a set of twenty-two playing cards that bear allegorical pictures, used in fortunetelling and as the trump cards in a game played with seventy-eight cards. |
| tungsten |
a chemical element that has seventy-four protons in each nucleus and that occurs in pure form as a gray metal solid with an extremely high melting point, used esp. in heat-resistant alloys and to make filaments for high-powered electric lamps; wolfram. (symbol: W) |