No.
A person can not be more than one third Irish, one third Japanese, and one third English. In terms of nationality you can not be more than 100 percent total. The fraction must add up to 100% and not go over.
Un terzo is an Italian equivalent of the English word "one-third (1/3)." The masculine singular cardinal number/indefinite article and noun also translate into English as "a third." The pronunciation will be "oon TER-tso" in Italian.
I believe the third is there in case one breaks.
Actually, 63% of all English words come from Latin.
"C" is the third letter of the English Alphabet
The third form of the English word "receive" is "received".
Roughly 30-40% of English words are of Germanic origin.
Third English Civil War happened in 1649.
"Third generation" in English is terza generazione in Italian.
"Le trois" translates to "the three" in English.
"(He) has" is an English equivalent of the French word a. The third person singular in the present indicative also translates literally as "It has," "One has" or "She has" in English. The pronunciation will be "ah" in French.