Sí

As defined by the Cleasby & Vigfusson Old Norse to English dictionary:

sí Old Norse word can mean:

sí

adv., contracted from sin, [Goth. sinteino = πάντοτε, sinteins = ἐπιούσιος, ὁ καθ ἡμέραν; O. H. G. sin- and sina- in several compds, e. g. sin-vluot, the great flood = the Deluge (whence by corruption the mod. Germ. sünd-fluth and Dan. synd-flod = the sin-flood); A. S. sin-; Lat. semper; see Grimm’s Gramm. ii. 554]:—ever; it is, however, used singly only in the phrase, sí ok æ, ever and aye, incessantly, but it is used in several compds as a prefixed particle.

sí

II. with part., as sí-étandi, sí-drekkandi, sí-sofandi, sí-talandi, sí-sníkjandi, sí-hlæjandi, sí-grátandi, sí-stelandi, sí-ljúgandi, sí-rennandi, etc.

sí

B. COMPDS: síbyrða, síbyrðis, síbyrt, sídægris, sífella, sífleyttr, sífrjór, síglaðr, sígrænn, síhverfr, símáligr, símælgi, síreiðr, sísoltinn, sívaf, sívalr, sívefja, síþögull.

Possible runic inscription in Younger Futhark:ᛋᛁ
Younger Futhark runes were used from 8th to 12th centuries in Scandinavia and their overseas settlements