Elements as「ejaculatory threads with head and neck in vagina」is the Japanese variant and not the original Chinese apparently, suggesting that perhaps it is better not to ejaculate into the vagina to avoid conception, and instead choose some other less dangerous environment to begin with, or, as a last resort, coitus interruptus: to CUT SHORT prior to ejaculation and by extension, TO PETER OUT. Note to non-English speaking readers: a 'peter' is an English vulgar slang euphemism often used to replace the word 'penis' that here means to pull peter out and exhaust its contents by some other method until diminished and COME TO AN END. Cause one's spermatozoa to DIE, DISAPPEAR, VANISH and not complete their sacredly ordained evolutionary duty of fertilizing a ripe ovum, the female gamete.
　Some suggest elements describe amputation of the penis for various causes: right element in Chinese (see related glyph 絕) was formerly not「colorful sex」but rather「ream, sever」over「penis in a sex hole vortex.」Nevertheless,「ejaculation with color」does also suggest a bloody or pus-laden discharge along with semen, symptoms that required castration as the treatment of last resort: TO CUT CLEANLY, SEVER COMPLETELY.
　May have referred to using a sword to cut free a human fetus or a non-human animal during an otherwise impossible birth. A「sword cutting」into a「vagina」as an ancient episiotomy, a surgical incision of the perineum to enlarge the vagina and so facilitate delivery during childbirth by CUTTING SHORT, CUTTING CLEAN the natural delivery, or, as a symphysiotomy and cutting the pubic bone (that bone matter within the mons pubis) in half, SEVER COMPLETELY INTO TWO PARTS, splitting into「two sides」by CLEAVING, SPLITTING OPEN the mother's birth canal and at times, also the infant's head:
　「Before the Caesarean section technique was available, if labor failed to progress because the head of the fetus was too large, the mother's symphysis pubis was cut and the skull of the fetus was crushed.」
　　[　https://en.wikipedia.org/wiki/Pubic_symphysis 2012-07-22　]　
　Clearly not a desirable situation for anyone concerned, ABSOLUTELY NOT, BY NO MEANS, that is UNSPEAKABLE.

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: variant of 絕|绝
Japanese: to sever, to cut off, to suppress, to abstain, to die out, to peter out, to become extinct, to cease, to be stopped, to be discontinued, to be cut off, to be unspeakable, to be unimaginable, to exterminate, to eradicate, to let go out, to cut apart
Unihan extended: cut
EDRDG: discontinue; beyond; sever; cut off; abstain; interrupt; suppress