External sources give as this glyph's definition,「teeth grown in old age」except that teeth do not grow in humans of older age. Most permanent teeth are in place by age seven, especially the very sharp incisors (「scissor teeth」that make 'incisions'), the second molar appears about age twelve, and the third molar normally by age twenty or so and perhaps in dynastic China a twenty-year-old service provider many have been considered fairly aged and over the hill. Nonetheless, even when the average human lifespan was merely thirty-five to forty years (not long ago for that matter), it is a stretch to call twenty 'old age.' More likely, these elements are「chewed to bits while copulating」and likely with「teeth of a young person」used on an old guy. This problem was another reason for dis-integrating the feet of young girls, since using the soles of their feet as masturbation aids precluded the need for inserting any vital pieces of living tissue of one's meat between a set of untrained or revengeful teeth.
　Conversely, an old person in ages prior to dental hygiene might not have had any teeth left to speak of, hence the lips and gums may have then become a「cavity with two sets of lips」: elements may be「gnawing with copulation」to describe a sensation with no teeth…imagine that.
　Without a doubt, the Irish also have knowledge of their own to pass along in these trying times:「Masturbation will not spread coronavirus, especially if you wash your hands (and any sex toys) with soap and water for at least 20 seconds before and after.」Nonetheless and regrettably, unlike in dynastic China, it must be undertaken alone to truly be a preventative countermeasure but still achieve the desired result with some degree of safety.
　 　[　https://www.sexualwellbeing.ie/sexual-health/sex-and-coronavirus/ 2020-03-31　]　
　The Dutch, too have the same solution—it seems masturbation has become mainstream in the media the world over due to the coronavirus (it has always been 'the main stream' in reality, albeit covertly for most folks):
　「'Don't have sex with your partner if they have been isolated because of (suspected) coronavirus infection,' the RVIM says. 'Sex with yourself or with others at a distance is possible (think of telling erotic stories, masturbating together).'」
　　[　https://www.theguardian.com/world/2020/may/15/dutch-official-advice-to-single-people-find-a-sex-buddy-for-lockdown-coronavirus 2020-05-16　]　
　Needless to point out perhaps, but Chinese shamans from antiquity hit upon the same solution as a pandemic preventative countermeasure, honed for ultimate client satisfaction by utilizing naked females with no-longer-integrated feet as masturbatory sex buddies available for short-term rental with erotic visualization of live prepubescent female genitalia engaging in autoerotic stimulation herself, as a solution to the same problem facing us now, but in pre-Internet days.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: teeth grown in old age
Unihan extended: teeth grown in old age
EDRDG: teeth grown in old age