Ingvaeonic Nasal Spirant Law - English

English

English shows the results of the shift consistently throughout its repertoire of native lexemes. One consequence of this is that English has very few words ending in -nth; those that exist must have entered the vocabulary subsequent to the productive period of the nasal spirant law:

• month - derives from Old English monaþ (cf. German Monat); the intervening vowel rendered the law inapplicable here.
• tenth - from Middle English tenthe. The original Germanic *tehundô, which was regularised to *tehunþô in early Ingvaeonic, was affected by the law, producing Old English teogoþa, tēoþa (Modern English tithe). But the force of analogy with the cardinal number ten caused Middle English speakers to recreate the regular ordinal and re-insert the nasal consonant.
• plinth - a loanword in Modern English from Greek (πλίνθος "brick, tile").

Likewise, the rare occurrences of the combinations -nf-, -mf- and -ns- have similar explanations.

• answer - originally had an intervening dental: Old English andswaru.
• unfair - the prefix un- is still productive.