pattern_is_full,
Well if we're going to be precise, putting the two words into google "with these" around them gives the following -
"Taxiway" - 2,260,000 results
"Taxyway" - 24,800 results
and
"Taxiing" - 2,870,000 results
"Taxying" - 196,000 results
It seems 'Taxi/Taxiing' it is then, not that it matters!