When my wife recently asked me if I knew what this word meant, all I could think of was the foul-mouthed Father Jack from the late, lamented comedy series Father Ted. His favourite word, which he voiced loudly, drunkenly and at any opportunity, was "feck". But while that may have made him a feckulent character, whether he was feculent is another matter entirely.
Feculent entered the English language in the mid 1400s, and must have been a useful word indeed at that time. It means turbid, filthy, fetid, abounding in dregs - the last of which is likely a euphemism for covered in s*** (and when you think about it, s*** is also a euphemism for the word which no spam filter will allow us to spell out in full).
As you might have gathered by now, feculent comes from the same word - faex - that gives us faeces. One notable characteristic of this word is that it only exists in the plural.
Another characteristic is the number of colloquial terms it's engendered, some of them taboo or at least considered offensive, and some so nauseatingly cute (poo poo anyone?) as to deserve way more opprobrium than their blunter cousins.
Then there is the weird term stool, used exclusively by the medical profession. It owes its existence to an obsolete piece of furniture called a stool of ease, which held a chamber pot and was kept in bedrooms for nighttime use. Yek!
One last story before we end this somewhat distasteful discourse. When I was about seven I developed an allergic rash to something on our farm which led to an outbreak of hives, a day of diarrhoea and, a couple of days in, sudden difficulty in breathing. The doctor was immediately summoned (this was a long time ago, remember) and on his arrival he asked me a number of questions, including "have you done any big jobs today?" In my innocence, I replied, "I helped my Mum put the groceries away." That was the day I learned yet another stupid colloquial term for - well, let's not say it again.