= Photius, Lexicon sigma120 (s.v. seirh=na), a close paraphrase of Harpokration (epitome) sigma2 Keaney, s.v. sei/rina, the plural form of the present entry's neuter headword. There is much variation in the mss. of all three lexica in the spelling of the primary headword and some of the secondary ones as well. For more on the issues, see Theodoridis on Photius ad loc. Apparently the point of Harpokration's entry was that the Athenian orator Lycurgus (fr. 5.10 Conomis) used the term in a sense that was not covered by the lexicographers. The present headword is otherwise unattested outside lexicographers.
On the garment(s) in question Theodoridis cites Gow's comments in his edition of Theocritus, Idylls 15.21.
[1] cf. Hesychius sigma340 (s.v. seirh/).
[2] cf. Hesychius sigma342, where a seiro/n is defined as a word used by Sikyonians for a man's summer-cloak.
[3] cf. Hesychius sigma342.
[4] cf. generally sigma 275, sigma 284, sigma 285.
[5] cf. sigma 476.
[6] Reading h)/ ('or') with Harpokration in place of the Suda's ei); cf. Theodoridis on Photius sigma120.
[7] The point being made here is rendered unclear by different formulations of it in the different lexica. In Harpokration Keaney prints "it is written without the 'e', [i.e.] sirina". The mss of Photius (noted by Theodoridis) have serh=na or se/rhna. The Suda version evidently intends to highlight a seirina/serina distinction.