<span class="searchmatch">semifactorials</span> plural of <span class="searchmatch">semifactorial</span>...
From semi- + factorial. <span class="searchmatch">semifactorial</span> (plural <span class="searchmatch">semifactorials</span>) (mathematics, combinatorics, rare) Synonym of double factorial. 1942 February, Giulio Racah...
monofactorial multifactorial nonfactorial plurifactorial polyfactorial <span class="searchmatch">semifactorial</span> subfactorial superfactorial trifactorial unifactorial primorial factorial...
mark (!!). For example, 9!! = 1 × 3 × 5 × 7 × 9 = 945. Synonym: (rare) <span class="searchmatch">semifactorial</span> 1902, Arthur Schuster, “On some Definite Integrals and a New Method...