[1545–55; under- + -most]This word is first recorded in the period 1545–55. Other words that entered Englishat around the same time include: caste, fusion, integral, inversion, sweetenunder- is a prefixal use of under, as to indicate place or situation below or beneath (underbrush; undertow); lower in grade or dignity (undersheriff; understudy); of lesser degree, extent, or amount (undersized); or insufficiency (underfeed)
Examples of 'undermost' in a sentence
undermost
The perches must be level, and not one above the other, or unpleasant consequences may ensue to the undermost row.
Mrs. Isabella Beeton The Book of Household Management (1861). Retrieved in 2019 from Project Gutenberg (https://www.gutenberg.org/ebooks/)