Singly means one at a time. Singly also means separately, apart from others, individually. Singly is an adverb, it dates from
Singularly is an adverb which means in an outstanding or remarkable way. Singularly may mean in a wonderfully outstanding or remarkable way, or in a strangely, bizarrely or heinously remarkable way. Singularly appears in the English language in the fourteenth century from the Latin singularis meaning one at a time, peculiar, remarkable.
Each strategy entails some kind of sacrifice–you can’t expect insurance to be free–but singly or in combination they may enable you to sleep better. (Forbes)
However, unlike spiders, which always produce a double thread (each with the ability to singly hold the animal’s weight, as an extra safety feature), Spider-Man more often than not shoots only from one wrist,” he said. (The International Business Times)
There are a few self fertile hollies available (I grew one in my last garden), but the berries tend to grow singly up the stem between the leaves which makes it difficult to get a good looking sprig for the top of your pudding. (The Torquay Herald Express)
It is one of the great humanitarian disasters of our time, and it has given a strategic beachhead to singularly demonic cult determined to spread terror, fear and death: ISIS. (The Des Moines Register)
A singularly excellent and original feature debut by French-Turkish director and co-writer Deniz Gamze Erguven, the film is a moving portrait of sisterhood, a celebration of a fierce femininity and a damning indictment of patriarchal systems that seek to destroy and control this spirit. (The Belleville News-Democrat)
Unfortunately, the singularly unique director with an eye for bloody action and an ear for catchy conversation has long said he will only make 10 films in his career. (Headlines & Global News)