1num.thirdly (in a series, sequence, etc.):
(1380) Et tiercement lour advis est [...]
iii 89
(1397) Tiercement, q'il appartient a [...]
iii 347
(1413) Secundement, pur bone governance et maintenance de ses loies deins le roialme. Tiercement, pur cherier les estrangiers ses amys
iv 3
[tercement] (1380)