underlayment
|un/der/lay/ment|
🇺🇸
/ˈʌndərleɪmənt/
🇬🇧
/ˈʌndə(r)leɪmənt/
layer placed beneath
Etymology
'underlayment' originates from English, specifically the combination of the word 'underlay' and the noun-forming suffix '-ment', where 'under' meant 'below' (Old English 'under') and 'lay' derived from Old English 'lecgan' meaning 'to place, to lay'.
'underlayment' developed from the verb 'underlay' (Old English elements 'under' + 'lecgan' → Middle English 'underleyen'/'underlien') with the later addition of the suffix '-ment' (used to form nouns), producing the modern noun 'underlayment'.
Initially the components referred to the action 'to lay under' or the idea of something 'placed beneath'; over time the combined form came to mean specifically 'a layer placed beneath (roofing or flooring) for protection or support'.
Meanings by Part of Speech
Noun 1
a protective or waterproof layer installed beneath roofing materials (such as shingles) to prevent water penetration and protect the roof deck.
The crew rolled out the underlayment before nailing down the shingles.
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Noun 2
a cushioning, leveling, or insulating layer placed between a subfloor and the finished floor (e.g., laminate, vinyl, or hardwood) to reduce sound, smooth minor irregularities, and sometimes act as a moisture barrier.
They installed a foam underlayment under the laminate to reduce noise and improve comfort.
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Last updated: 2025/12/19 04:37