It seems odd that the continual tense of "to panic" is "panicking". Or "picnic->picnicking". When did the "k" get added, and why? Surely the natural extension would be "paniccing" if one wished to preserve the hard "c" sound visually and avoid "-ici-" and its intuitive soft "c"?
Does that rule also apply to all verbs ending in -ic? For example if we had verbs "to lyric [a song]" or "to topic [a forum post]"? I can't think of other examples!
Does that rule also apply to all verbs ending in -ic?
Yes.
There are very few verbs that end with -ic and almost all of them have the letter k in their progressive (-ing form) and participles (-ed form).
We add the letter k to their progressives and participles because we want the original pronunciation with the /k/ sound in their inflections. And if we don't add the letter k, the pronunciation will change (i.e. it will become /s/ rather /k/).
The letter c often gives the /k/ sound when it comes before the letters a (e.g. car), o (e.g. cot) or u (e.g. cup), or it's at the end (e.g. panic). Or when it comes before the letter k (e.g. pick).
By contrast, it gives the /s/ sound when it comes before the letters e (e.g. cent), i (e.g. city) or y (e.g. fluency).
Panic has the /k/, and if we don't add the letter k to its progressive or participle, its pronunciation will change from /k/ to /s/:
Therefore, mimic becomes mimicking/mimicked, frolic becomes frolicking/frolicked, traffic becomes trafficking/trafficked, magic becomes magicking/magicked etc.
And almost all other verbs that end with -ic have -ck- in their progressives and participles.
So the main purpose of adding the k is to keep the original pronunciation.
-ck(including panick). After reform it became -c, but spelling in -ing form had remained.
It's the rule of adding endings to verb. Rules sounds like:
If the verb ends with a single vowel plus a consonant, and the stress is at the end of the word (e.g. refer), then you need to double the final consonant before adding -ed and –ing:
If the verb ends with a vowel plus a consonant and the stress is not at the end of the word, you don’t need to double the final consonant when adding -ed and -ing
Tf the verb has only one syllable and ends with a single vowel plus a consonant (e.g. stop), then you need to double the final consonant before adding -ed and -ing.
If the verb ends with two vowels plus a consonant, you should generally not double the final consonant.
If the verb ends in -c (e.g. panic), you need to add a -k before adding -ed and -ing, and also -er.
