Lippage unfortunately occurs when one tile edge is higher or lower than the adjacent tile. This topic continues to receive a significant amount of coverage in written documents as well as everyday conversation. The reason lippage is constantly being discussed is because it occurs entirely too often.
According to the chart on “Flatness and Lippage” found in the TCNA Handbook, lippage can be measured and has an allowable limit. For pressed floor and porcelain tiles, of all sizes, with a grout join of 1/16" to less than ¼", the allowable lippage is 1/32".