:I totally defer to AlanE on these matters. He is probably the most literate person here. My own view is that, when a phrase is used as a noun, as in "thermodynamics was developed in the 19<sup>th</sup> century", there is definitely no hyphen. 19<sup>th</sup> is an adjective and century is a noun. But in "thermodynamics is a 19<sup>th</sup>-century development" I tend to use a hyphen, because the whole thing is a noun phrase. But I see that Alan has just made a judgment on this [http://www.conservapedia.com/index.php?title=Stabat_mater&curid=79536&diff=1272688&oldid=1272516 here]. I defer to him. [[User:SamHB|SamHB]] ([[User talk:SamHB|talk]]) 23:21, 24 August 2016 (EDT) | :I totally defer to AlanE on these matters. He is probably the most literate person here. My own view is that, when a phrase is used as a noun, as in "thermodynamics was developed in the 19<sup>th</sup> century", there is definitely no hyphen. 19<sup>th</sup> is an adjective and century is a noun. But in "thermodynamics is a 19<sup>th</sup>-century development" I tend to use a hyphen, because the whole thing is a noun phrase. But I see that Alan has just made a judgment on this [http://www.conservapedia.com/index.php?title=Stabat_mater&curid=79536&diff=1272688&oldid=1272516 here]. I defer to him. [[User:SamHB|SamHB]] ([[User talk:SamHB|talk]]) 23:21, 24 August 2016 (EDT) |