First, I think it would be good to know what you think is indicated by a "womb".  I understand that as an incubator.  A vessel that holds a seed and developes it.  But I do not think that fits at all with the DDJ 5 nor 6.  Perhaps you are understanding it differently?  Or perhaps all that you are saying is, "it's not male and pointy"?   Second, DDJ 6?  This is the version I am looking at.  谷神不死，是謂玄牝。玄牝之門，是謂天地根。綿綿若存，用之不勤.  - Source Are we using the same version?  You're saying the 6th character is 胃, I'm seeing it as 謂.  They appear similar, but, are they?  Since you still haven't brought your own translation of the remainder of DDJ 5 which seems to clarify the meaning of  橐 籥, I'll go ahead and do my best to translate DDJ 6 and maybe you will correct it using whatever resources you choose to use.   谷 Valley 神 [of the] spirit 不死 immortal， 是 Truly 謂 _______ 玄 mysterious 牝 female 。 玄 Mysterious 牝 female 之 she is a 門 gate， 是 Truly 謂 _______ 天地 heaven-and-earth 根 roots/rooting。 綿綿 Streaming-continuously 若  seems 存 to issue forth， 用 Therefore 之 she [is] 不勤 effortless.   So, DDJ 6 is describing a valley, which is continuous, a gate, which is long and slender. 謂 is generally translated as "named" or "called" which fits nicely.  At the very least, the stanzas need a verb, don't they?   ...truly it is named, 玄牝, lady-of-mystery. ...truly it is named, 天地根, root-of-heaven-and-earth.   or   ...truly womb lady-of-mystery. ...truly womb root-of-heaven-and earth.   Is a womb streaming-continuously?  綿 is wool or silk. Is a womb like a root coming off the bottom of a plant?   根 are literally roots. Is a womb like a valley? Is a womb like a gate?   A womb incubates then in a sudden furious ordeal delivers with contractions.  That's not what's happening here.  This is smooth and effortless.     The challenge is:     A chinese text of this vintage making the comparison that you made:  The bellows is a euphemism for 'willie', and  橐 籥 is a euphemism for a womb.   From what I'm seeing, there is maybe some feminine imagery in 4 verses.  But this depends on what is considered feminine.  Are we talking about open/closed?  full/empty?  pointy/round?  provider/reciever?  My understanding is the philosophy brought in the DDJ is about coexisting, coequal, codependent opposites.  But I'm not seeing anything womb-like in these descriptions.