elvish tattoo.

[Galin]

William Womack seems to have coined a Neo-elvish word.

amortale: "uprising, rebellion, revolt" < Qw amorta-, see amortar
amortar: "upriser, insurgent, rebel" < QW amorta- "heave" lit. "rise up," cf. E ama, "up"+ E orta- "rise"

Tolkien didn't write this, and you probably don't want Neo-stuff though.

Anyway I think you would be safe with rómen (the one that looks like a y), based on The King's Letter, an English version where JRRT wrote rekkoning for example. Arden Smith notes (Vinyar Tengwar 29) on the usage with respect to this version in general:

'Doubled letters are generally indicated by means of the letter-doubling tehta. Exceptions are Stirring (line 22), which has the doubled letter written out in full, and will (line 5) and all (line 10), both of which use the letter alda instead of lambe + tehta.'

This information is based on this example of course. Also, the English letters to Sam reflect English orthography more than phonology -- on this point Arden Smith notes the rendering of 'Bridge' as bridge rather than brij.

I would choose the letter-doubling tehta in general, as the third copy of the English version uses this for will (line 5) though all (line 11) still shows alda. The tehta looks sort of like this ~ though perhaps more like a dash, and goes 'inside' lambe.

JRRT himself did not publish these versions of the King's Letter, but they now appear in both Vinyar Tengwar and The History of Middle-Earth series. They are versions of King Elessar's letter to Master Samwise. Arden Smith writes: 'Each of the six texts (three in English, three in Sindarin) is unique in one way or the other, and all six employ symbols and conventions not found in any other published example of the Tengwar.'

In any case I'm not an expert but maybe this might help. Usually with a tattoo I recommend people pick something they like that's already attested or published by Tolkien.

Of course that limits people, but just to toss it in