Well, there doesn't seem to be anything to differentiate here, so my guess is that X = consonant, and . = vowel. So we'd have an eight letter word, running v-c-v-c-c-v-T-c. My guess is the final combo is one of a limited number of options - most likely H, S, or another T.
Of course, that's just speculation, and not much use at this point.
Could it be E T E R N I T Y? That relates to the ouroboros symbol.