Where does “nappy check” come from?

nappy check (English) comes from English nappy, from English NAP, from French napper, from French -er, from English -er, from Middle English -er, from Old French -er, from Latin -āre — he, she.

Ancestry of “nappy check”, step by step

nappy check traces back through two separate lines of ancestry.

via English nappy

StepLanguageWordMeaning
1EnglishnappyAn absorbent garment worn by a baby who does not...
2EnglishNAPAcronym of non-aggression principle; Acronym of...
3Frenchnapperto cover
4French-erForms infinitives of first-conjugation verbs
5English-erA person or thing that does an action indicated...
6Middle English-eragentive suffix; agent noun suffix
7Old French-erAlternative form of -ier, verbal suffix;...
8Latin-ārefirst conjugation
9Proto-Italic-āōForms primarily denominative verbs
10Proto-Indo-European-eh₂yétiCreates iterative/ frequentative/ intensive...
11Proto-Indo-European-yétiCreates intransitive, often deponent,...
12Proto-Indo-Europeanyé-
13Chichewaiyehe, she

via English check

StepLanguageWordMeaning
1EnglishcheckA situation in which the king is directly...
2EnglishchequerThe edible fruit of the wild service tree,...
3Old Frencheschequierexchequer
4Medieval Latinscaccariumchess board; chessboard; exchequer
5Vulgar Latinscaccuschess
6Arabicشَاهking in chess; king; king or check at chess, shah
7Persianشاهking; shah; king; Something that is the biggest...
8Middle Persian𐭬𐭫𐭪𐭠king
9Old Persian𐏋king
10Proto-Iranianxšáyati
11Proto-Indo-Iraniankšáyatihe rules, he has power over
12Proto-Indo-Europeanteḱ-to sire, beget
Every word from Chichewa iye