From the active participle of verb ܐܵܠܹܨ (ālēṣ) + -ܝܐ (-āyā, the attributive adjective ending).
ܐܵܠܨܵܝܵܐ • (ālṣāyā) (feminine ܐܵܠܨܵܝܬܵܐ (ālṣāytā), plural ܐܵܠܨܵܝܹ̈ܐ (ālṣāyē))