-и́ть (-ítʹ). An early 20th-century formation. IPA(key): [strɐjˈnʲitʲ] <span class="searchmatch">стройни́ть</span> • (strojnítʹ) impf (no perfective form) to cause one to look more slender...
lose weight? Conjugation of полни́ть (class 4b imperfective transitive) <span class="searchmatch">стройни́ть</span> (strojnítʹ) полня́щий (polnjáščij) Directly or via Old Church Slavonic...