A. Verb.
Yâchaś (יָחַשׂ, Strong's #3187), “to reckon (according to race or family).” In Aramaic, yâchaś appears in the Targumim for the Hebrew mishpachah (“family”) and toledot (“genealogy or generations”). This word occurs about 20 times in the Old Testament.
In 1 Chron. 5:17 yâchaś means “reckoned by genealogies”: “All these were reckoned by genealogies in the days of Jothan King of Judah …” (cf. 1 Chron. 7:5). A similar use is found in Ezra 2:62: “These sought their register among those that were reckoned by genealogy, but they were not found …” (NASB, “searched among their ancestral registration”).
The Septuagint renders yâchaś variously: ogdoekonta (“genealogy … to be reckoned”); arithmos (“member of them; father their genealogy”); paratoxin (“member throughout the genealogy”); sunodias (“reckoned by genealogy”).
B. Noun.
Yachaś (יַחַשׂ, Strong's #3188), “genealogy.” This word appears in the infinitive form as a noun to indicate a register or table of genealogy: “And the number throughout the genealogy of them that were apt to the war, and to battle was twenty and six thousand men” (1 Chron. 7:40; cf. 2 Chron. 31:18). Another rendering concerning the acts of Rehoboam, recorded in the histories of Shemaiah (2 Chron. 12:15), meant that the particulars were related in a genealogical table.