The word "rhusin" has an unconventional spelling, but it can be deciphered with the help of IPA phonetic transcription. In IPA, "rh" represents the sound /r/, while "u" represents the sound /ʌ/. The next letters "si" represent the sound /s/ followed by the diphtong "in" for the sound /aɪn/. So, "rhusin" is pronounced as /rʌsɪn/ and refers to a substance found in sumac. While the spelling may be confusing at first, understanding its pronunciation makes it easier to use in language and communication.
A concentration product of rhus glabra, employed as an intestinal astringent in doses of gr. 1-2 (0.06-0.13).
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.