PCO stands for Potential Change Order (construction management). Suggest new definition. This definition appears somewhat frequently and is found in the following Acronym Finder categories: 1  Business, finance, etc.
Quick Answer. The Roman numeral XIX is the number 19. X is the number 10, and I is the number one. When a lower number is placed in front of a larger number, it indicates subtraction; IX is the same as 10 minus one, which equals nine. The Ancient Romans used different letters to represent numbers.
The noun XI has 2 senses: 1. the cardinal number that is the sum of ten and one. 2. the 14th letter of the Greek alphabet. Familiarity information: XI used as a noun is rare. â¢ XI (adjective). The adjective XI has 1 sense: 1. being one more than ten. Familiarity information: XI used as an adjective is very rare.