Are the words "sillily", "uglily", "friendlily", "livelily", etc., valid English?

I have wondered about how to make the words silly, ugly, friendly, lively, etc. into adverbs, so I researched in the Internet. I found many different answers, so I tried checking Oxford Dictionaries.

However, Oxford Dictionaries still gave me two answers:

• this is from Oxford Dictionaries’ online grammar reference, “forming adverbs” page

  Adjectives that end in -ly, such as friendly or lively, can’t be made into adverbs by adding -ly. You have to use a different form of words, e.g. ‘in a friendly way’ or ‘in a lively way’ instead

• from the dictionary entries: there are results from typing sillily, uglily, friendlily, livelily into Oxford Dictionaries’ website (online dictionary)

That’s quite an obvious contradiction from one of the most famous dictionary providers of the world!

So, are the words sillily, uglily, friendlily, livelily, etc. valid English?

Note: I already saw the “comparative and superlative adverbs” question that asked about the word sillily but I don't see any sources in there that are trustworthy enough (compared to oxford dictionaries), so I'm asking a new question.

EDIT: I've already reported the mistake to Oxford Dictionaries. They said that those words are valid (although rare) and it's a mistake in the reference, They say they will get it fixed soon.

If you use the real OED, you will find all these with no trouble:

burlily, chillily, cleanlily, comelily, deadlily, friendlily, ghastlily, ghostlily, godlily, holily, homelily, jellily, jollily, kindlily, livelily, lonelily, lordlily, lovelily, lowlily, manlily, melancholily, oilily, portlily, sicklily, sillily, sprightlily, statelily, surlily, uglily, unfriendlily, ungodlily, unholily, unmanlily, wilily, woollily, worldlily.

So there is clearly ample evidence that this sort of thing exists.

Here in more detail is the OED entry for sillily:

sillily [ˈsɪlɪlɪ], adv.

Etymology: f. silly a. + -ly ².

1. Poorly, badly. Obs. rare.

   • 1581 Mulcaster Positions xxxv. (1887) 126 — The soule it selfe is but sillyly looked to, while the bodie is in price.
   • 1611 Cotgr., s.v. Manger, — He that makes himselfe simple shall be sillily vsed.

2. In a foolish, absurd, or senseless manner.

   • 1627 W. Sclater Exp. 2 Thess. (1629) 256 — How doe wee sillily call all Idolatrous, that is in vse amongst Idolaters?
   • 1658 A. Fox Würtz’ Surg. iii. xi. 248 — Such Wounds which were very deep, and were silily and ignorantly stitched.
   • 1712 Steele Spect. No. 466 P6 — [She] affects to please so sillily, that..you see the Simpleton from Head to Foot.
   • 1740–1 Richardson Pamela I. xxiv. 67 — He sat down, and look’d at me, and..as sillily as such a poor Girl as I.
   • 1805 Spirit Publ. Jrnls. IX. 4 — They sillily interested themselves in the event of a new experiment.
   • 1843 Mrs. Carlyle Lett. I. 254 — Neither have I sillily paid four or five pounds away for it.
   • 1864 Browning Dram. Pers. Wks. 1896 I. 573/2, — I took your arm And sillily smiled.

So it has clearly been around for a long time.

That should answer your question about whether sillily is “valid English”. Sure, you may not care for it, but it is unquestionably an English word of long-standing use.

The only author I have read who regularly used the type of -lily ending discussed here is the novelist James Branch Cabell, who did it frequently enough that it ceased to be distracting to me and became instead a kind of characteristic ornament of speech in the faux-medieval fantasy world he wrote about.

In Figures of Earth (1921), for example, Cabell used seven different words with -lily endings:

"For, when we have achieved our adventure," says Manuel, "and must fight against each other for the Count's daughter, I shall certainly kill you, dear Niafer. Now if you were a Christian, and died thus unholily in trying to murder me, you would have to go thereafter to the unquenchable flames of purgatory or to even hotter flames: but among the pagans all that die valiantly in battle go straight to the pagan paradise. Yes, yes, your abominable religion is a great comfort to me."

and:

"Why, as always, Sister, I must follow my own thinking and my own desire," says Manuel, lordlily, "and both of these are for a flight above pigs."

and:

"One thing at least is certain," remarked King Helmas, frowning uglily, "and it is that among the Peohtes all persons who dispute our prophecies are burned at the stake."

and:

Now Manuel, driven out of Poictesme, went with his wife to Novogath, which had been for some seven years the capital of Philistia. Queen Stultitia, the sixtieth of that name to rule, received them friendlily. She talked alone with Manuel for a lengthy while, in a room that was walled with glazed tiles of faience and had its ceiling incrusted with moral axioms, everywhere affixed thereto in a light lettering of tin, so as to permit of these axioms being readily changed. Stultitia sat at a bronze reading-desk: she wore rose-colored spectacles, and at her feet dozed, for the while, her favorite plaything, a blind, small, very fat white bitch called Luck.

and:

Statelily the bird lighted on the window sill, as though he were quite familiar with this way of entering Manuel's bedroom, and the bird went in, carrying the child. This was a high and happy moment for the fond parents as they watched him, and they kissed each other rather solemnly.

and:

Harshly he answered: "Oho, I am not proud of what I have made of my life, and of your life, and of the life of that woman yonder, but do you think I will be whining about it! No, Freydis: the boy that loved and deserted you is here,"—he beat upon his breast,—"locked in, imprisoned while time lasts, dying very lonelily. Well, I am a shrewd gaoler: he shall not get out. No, even at the last, dear Freydis, there is the bond of silence."

and:

"I cannot tell you," replied Ruric, laughing sillily, "but in place of it, I will tell you a tale. Yes, yes, Count Manuel, I will tell you a merry story of how a great while ago our common grandmother Eve was washing her children one day near Eden when God called to her. She hid away the children that she had not finished washing: and when the good God asked her if all her children were there, with their meek little heads against His knees, to say their prayers to Him, she answered, Yes. So God told her that what she had tried to hide from God should be hidden from men: and He took away the unwashed children, and made a place for them where everything stays young, and where there is neither good nor evil, because these children are unstained by human sin and unredeemed by Christ's dear blood."

All seven of these words appear in the OED list that tchrist provides above. For what it's worth, I note that of the seven words only friendlily avoids the red-squiggly-line seal of disapproval in Microsoft Word.