Picture a ruler cut into three steps, and this word placing something on the third step. That is all the word itself says: third step of somebody's scale. It does not say whether step three is the worst or the mildest — the person who built the scale decided that. Burn doctors built theirs by depth, so step three is the deepest. American courts built theirs by seriousness, and they count , so step three is the lightest.
Two branches
燒傷的三度：往下看有多深
這把尺是按傷得多深排的，所以第三格在最底下，也就是最嚴重。
adjective · B2
Used in 'third-degree burn' for the most serious kind of burn: one that goes all the way through the skin and damages the tissue underneath. It usually appears in the plural, as 'third-degree burns'.
三度（燒傷）
罪名的三級：往下數有多重
同一把三格的尺，但這次是法院在訂，而且從最重的往下數，所以第三格反而最輕。
adjective · C1
Used in American law, in names like 'third-degree murder' or 'third-degree burglary', for the least serious of three levels of a crime — for example when the act was not planned, or when other facts make the court treat it as lighter.
三級（罪名）