Lewis Short
(adverb) : ĕā-tĕnus, is, designates the limit to which an action or condition extends
* So far (rare; perh. not before Cic., for in Plaut. Most. 1, 2, 50, the right reading is protenus); followed by quatenus, Cels. 2, 10; Dig. 47, 2, 92: caules lactucae ab imo depurgatos eatenus, qua tenera folia videbuntur, etc.,Col. 12, 9, 1; followed by qua, id. 4, 7, 2; id. Arb. 8, 2; Quint. 1, 11, 1.— With quoad: hoc civile, quod vocant, eatenus exercuerunt, quoad populum praestare voluerunt,Cic. Leg. 1, 4, 14; id. Q. Fr. 1, 1, 3; id. Univ. 11.—With ut, to such a degree, to that extent: verba persequens eatenus, ut ea non abhorreant a more nostro,Cic. Opt. Gen. 7 fin.; Cels. 5, 26; Col. 5, 1, 3.—Cf. with ne, Cels. 6, 6; Suet. Tib. 33; Just. 5, 10.
* Of time, so long, hitherto (late Lat.), Capitol. Gordian. 22; Oros. 6, 1.
Charlton T. Lewis, Charles Short, A Latin Dictionary