neuter
Thāvareyya (neuter) [from thāvara 2 ] the rank of a Thera. A I 38; II 23. This has nothing to do with seniority. It is quite clear from the context that Thera is to be taken here in the secondary sense explained under Thera. He was a bhikkhu so eminently useful to the community that his fellow bhikkhus called him Thera.
stability; continuance; being firm, long lasting
(nt, nt, abstr, from thāvara) stability; steadiness; steadfastness stability; continuance; being firm, long lasting [lit.] standing strong state Construction: √ṭhā + [v] + ara + eyya thāvara + eyya