A kenning is a distinctive feature of Anglo-Saxon and Old Norse poetry. Essentially, it is a type of metaphor, but particularly it is a compound expression which would have a generally understood meaning within the cultural context in which the original poet was composing. A very well known example of an Anglo-Saxon kenning is "hronrade," or "whale-road." This kenning appears in line 10 of the Beowulf poem and is a metaphorical expression meaning "the sea." Another good example in the early part of the poem is "sundwudu," or "sea-wood," in line 208. This is a metaphorical expression commonly used in Anglo-Saxon poetry to refer to ships or other water-faring vessels—literally, wood that is meant for the sea. Cultural understanding is necessary to know that a ship is meant, rather than simply flotsam and jetsam or driftwood.

Anglo-Saxon poetry also uses alliteration—repetition of the same first letter at the beginning of words placed close to each other—throughout. Because the poetry does not rhyme, this alliteration is a key part of what lends the poems their cohesion. Alliteration was supposed to help the sceop, or speaker of the poem, remember what comes next, and also to keep the rhythm. So for example we find "flota famiheals fugle gelicost," in line 218—this means "the remarkably bird-like foamy-necked floater," but in the Anglo-Saxon, with the alliteration, it is much more rhythmic and memorable! You can find other examples in line 208 ("sundwudu sohte," they sought the sea-wood) and elsewhere.

A kenning is generally a two-word, figurative substitution used in place of a noun. Kennings are interesting because they are an example of the ancient author and story-teller using figurative language before they realized exactly what figurative language was. I tell my students that they are especially effective because they encouraged the listener to figure out something on his own - kind of like an easy riddle within the text that kept them interested and active in the story-telling process. Some examples in the text are whale-road (line 10 - ocean), word-hoard (line 258 - vocabulary) war-board (line 438 - shield). As you can see, these require the listener or reader to sort of figure out exactly what the compound word references. 

Alliteration is repetition of similar consonant sounds. Again, similar to kennings, alliteration was used in this ancient text before the author or listeners knew exactly what it was. They did, realize, however, that it is pleasing to the ear to hear alliteration, which is important because Beowulf was originally told aloud. Some examples are: "Whichever one death fells must deem it a just judgment by God" (lines 440-441) and "He will carry me away as he goes to ground, gorged and bloodied" (lines 446-447). Once these are identified, it's easy to see that they create a more pleasing effect on the listener. 

Kenning is a poetic phrase using figurative language that refers to a noun. This form of figurative language has been used and associated with Anglo-Saxon poetry. Beowulf is an Old English poem done by an anonymous poet of Anglo-Saxon origin, and thus, it is expected that there is use of Kennings within the poem. Kennings often consist of two words separated by a hyphen and some of the example in Beowulf include;

• Dark death-shadow, this word was used to describe Grendel’s origin. It was used to show that death and Grendel were inseparable.
• Stout-hearted men, this phrase was used to refer to Scyldings, and it means the men were courageous.
• Swan-road, this word is used by Beowulf when he was planning his trip to King Hrothgar’s kingdom, and the word means ocean or sea.

Alliteration is a stylistic device that employs some form of repetition where the phrase is made up of similar sounding words. In Beowulf, some of the examples include;

• “Ride his steed to the strand” this phrase shows use of consonants to produce a similar sound in words. The phrase is used when Beowulf and his companions reach the shores of Hrothgar’s kingdom, where they meet a sentry on his horse.
• “Doing black deeds in the dead of night”, this phrase is used by Beowulf when he makes known his intention to Hrothgar’s sentry at the shores when they arrive in the land of the Danes.

A kenning is a figurative literary device, usually a compound expression used in place of a name or noun. Kennings is Old English poetry function in much the same way as epithets in classical epic poetry. All my examples come from the 2000 Seamus Heaney bi-lingual edition.

• "each clan on the outlying coasts beyond the whale-road (sea/ocean) had to yield to him"-line 10
• "the treasure-seat (throne) he was kept from approaching"- 168

Alliteration is the repetition of beginning consonant sounds in two or more words. Common, exaggerated examples are children's tongue twisters. Alliteration in literature is usually more subtle, and in "Beowulf", nearly every line utilizes the device.

• "Then as dawn brightened and the day broke"- line 126
• "the storied leader, sat stricken and helpless"- line 130