The word 'ten-thirty' is a modern English compound noun formed by combining two cardinal numbers. The first element, 'ten', descends from the Proto-Indo-European root déḱm̥t, which is the ancient source for the number ten across many Indo-European languages. The second element, 'thirty', is itself a compound from Old English, literally meaning 'three tens'. The logic of the compound is purely numerical and chronological, directly indicating a specific point on the clock face: thirty minutes past the hour of ten. This transparent method of time-telling reflects a straightforward, analytical approach to language, where existing number words are combined to create precise temporal designations without metaphorical shift.

Structure: ten (number) + thirty (number) - ten: From Old English 'tēn', 'tīen', from Proto-Germanic tehun, from Proto-Indo-European déḱm̥t. Functions as the cardinal number ten. - thirty: From Old English 'þrītiġ', from Proto-Germanic þrīz tigiwiz (three tens), from þrīz (three) + tigiwiz (group of ten). Functions as the cardinal number thirty.