Amlaith 1st king of Arthedain

I'm still going over names. Is it possible that 'laith' originated from the Gomish word 'laith¹', a noun meaning 'time, the course of time; (properly) lapse', thereby suggesting 'up time'? Could it imply rising to become the first king? Just a thought – maybe I'm reading too much into it.

On another note, I was thinking about 'Amon Darthir', and its etymology. The name might be a combination of the words 'dartha-', as suggested by elfdict.com, meaning 'to endure' or 'to last', and the latter being 'hîr', meaning 'lord'. This suggests that 'Amon Darthir' could be translated as 'Hill of the Enduring Lord'. This interpretation, which aligns with its location near the house of Húrin, symbolizes endurance or resilience, qualities that are strongly associated with Húrin's character and legacy. This thought came to mind as I pondered the significance of the mountain's name in relation to its surrounding lore.

We cannot say for sure what Tolkien's intention was with the name Amlaith. Mark Fisher suggested it might contain the elements am [up; upwards] and laith [an unglossed word also found in Limlaith referring to the clarity of its bright waters]. I'm not sure, if the Gnomish word laith would be directly transferable to Sindarin or rather be lith.

Maybe the second element is glaith instead with a probable meaning like polish; gloss; brilliance; light, so that Amlaith would mean "High-brilliance" and Limlaith would mean "Swift-brilliance". But these are just my assumptions.

Amon Darthir could mean "Hill of the Enduring Lord" based on your explanation. But I'm not sure if the i in hîr would trigger an internal i-affection, so "Enduring Lord" would be derthir instead. But there are examples of compound words with hîr with internal i-affection as well as examples without.