Bekhorot 30: words to know

הֶחָשׁוּד עַל (hechashud al): one who is suspected of violating. Used in the mishna regarding unreliability concerning tithes or Shemittah prohibitions.
דִּבְרֵי חֲבֵירוּת (divrei chaveirut): rules of fellowship regarding purity and tithes. Refers to commitments accepted by an individual to become a trusted haver.
עַם הָאָרֶץ (am ha'aretz): person unobservant of tithes and ritual purity. Introduces the baraita discussing someone non-scrupulous who undertakes to become a haver.
מִדִּבְרֵי סוֹפְרִים (midevrei soferim): from rabbinic enactments. Employed to show that a prospective convert must accept even rabbinic nuances.
תַּלְמִיד חָכָם (talmid chakham): Torah scholar. Debated regarding whether he needs formal initiation before three haverim.