That is the singular form; the plural form is those.
Bacterium is the singular word.
the singular word it is salmon.
singular
Adenoma is the singular of adenomata.
The word 'Phenomenon' is singular. The plural form is 'Phenomena'.
singular of the word stitches is stitch.
Lance is singular.
The word "hang" is singular.
Yes, the word "document" is singular.
The word dog is the singular form.
The singular form of the word flagella is flagellum.
The word "influx" is singular. It refers to the act of flowing in.