There are a number of homophonic words in English, some of which cause no end of confusion. One of those is the word slew, or slough, or even, slue. All of which are pronounced "slew." We have, in other words:

The word slew, the past tense of the verb slay; there's the slew that's a variant spelling of slough:

1. A depression or hollow, usually filled with deep mud or mire.
2. also slue A stagnant swamp, marsh, bog, or pond, especially as part of a bayou, inlet, or backwater.
3. A state of deep despair or moral degradation.

And we have the slew I want to talk about today:

Slew, meaning "A large amount or number; a lot: a slew of unpaid bills." Although slew is a venerable word, you'll note that the AHD labels it as "informal." Slew has become oddly popular in colloquial every-day-English in the last few years. Moreover, slew seems almost exclusively American, though though it is sometimes spelled slue.

Slew comes to Modern English via Irish Gaelic sluagh, multitude, from Old Irish slúag. It's interesting that it seems to have come directly from Irish, to American. The OED notes that the first attested use of slew is in 1839 in D. P. Thompson's Green Mountain Boys "He has cut out a road, and drawn up a whole slew of cannon clean to the top of Mount Defiance" (II. x. 145 ). I suspect slew is a loan word brought to the U.S. by nineteenth century Irish immigrants.

Slew is not the only word in Modern English derived from Irish sluagh; there's the modern English word slogan, as well. The AHD defines the noun slogan as:

1. A phrase expressing the aims or nature of an enterprise, organization, or candidate; a motto.

2. A phrase used repeatedly, as in advertising or promotion: "all the slogans and shibboleths coined out of the ideals of the peoples for the uses of imperialism" (Margaret Sanger).

3. A battle cry of a Scottish clan.

That last definition "A battle cry of a Scottish clan" gives a clue to the is the one that's a dead giveaway regarding the Gaelic heritage and etymology of slogan: "Alteration of Scots slogorne, battle cry, from Gaelic sluagh-ghairm: sluagh, host + gairm, shout."

Our modern English Slogan comes from Irish Gaelic sluagh, "multitude," from Old Irish slúag. In Old Irish slúag is used to refer to a "host," or multitude in the sense of an army, or a hunting (or cattle-raiding) party, or a group of fairies. Slogan is the shout or war-cry of the clan. It's not all that far from war-cry, to the modern use of political and advertising slogans.

Slogan seems, according to the OED, to have first entered English via the work of the middle Scots writer Gavin Douglas (1475?–1522), in his translation of the Aeneid. Douglas was the first to translate Virgil's poem into English, and the translation was almost immediately popular, and remained so for many years, even into the eighteenth century. In fact, Douglas' use of slogorne inspired the latter (and fairly minor) poet Thomas Chatterton (1752–1770). Middle Scots, like Middle English is not a language with rigid spelling rules. The edition of Gavin Douglas' Aneid that Chatterson used spelled slogorne as slughorne. Douglas' lines "The deaucht trumpet blawis the brag of were; the slughorne, enseule or the wache cry went for the battall all suld be reddy," (Douglas' Aneid (Bk. VII. xi. l. 87) was perhaps too laden with Scots for Chatterton to understand that the slughorne, was the "wache cry," the alert, the war-cry. Chatterton thought slughorn was a horn or trumpet used in war, much like the modern bugle. When Chatterton used the word slughorn in his poem medieval set and inspired "The Battle of Hastings" "some caught a slughorne and an onsett wounde" (ii 99) to refer to a war-trumpet, Chatterton was in turn followed by the much more popular poet Robert Browning in his poem "Childe Roland to the Dark Tower Came" to refer to a war-trumpet:

I saw them and I knew them all. And yet
Dauntless the slug-horn to my lips I set,
And blew (xxxiv ll. 4–6).

And all from the Old Irish slúag "host."