Lease in line 4 means, essentially, allotted time. Though the word often refers to a legal contract—for example, an agreement to rent an apartment—Shakespeare uses it here to refer simply to a limited span of time.

(a)  

Complexion refers to the natural appearance of the skin, especially the skin of the face. In the poem, the speaker personifies the sun, giving it skin, in order to compare it to the young man's own complexion.

(a)  

One often uses the word "fair" when talking about whether something is just or unjust: one might say, for instance, that someone's prison sentence was fair or unfair. Shakespeare uses the word in a different sense. Here it refers to physical beauty. In the Renaissance, to call a man fair was to suggest that he was exceptionally beautiful.

(a)  

"Untrimm'd" means stripped of ornament or plain.

(a)  

To own or control something. The word ricochets against the word "lease" in line four. In contrast to the beauty that summer merely rents, the young man's beauty is his property, something he controls forever.

(a)  

The word is a contraction of the verb "own," meaning to possess something. It works together with the word "possession" earlier in the line to give the strong sense that the young man's beauty is his property, permanently.

(a)  

a young woman, but the word can also refer to her state of maidenhood—that is, being a virgin.

(a)  

angels

(a)  

To covet something is to desire it strongly. Here, it also calls to mind the ninth Commandment from the Bible: "Thou shalt not covet thy neighbor's wife."

(a)  

This is slightly ambiguous. It could mean family members of Annabel Lee, who are of high social class. Or it could be a reference to the angels: "highborn" because they come from heaven, and "kinsmen" because Annabel Lee is herself angelic.

(a)  

in this sentence means "took", "carried"

(a)  

A small room or tomb in which a dead person is laid to rest.

(a)  

This means the angels were actively jealous of the speaker and Annabel Lee.

(a)  

to divide or separate.

(a)  

Beams means "shine," but it also has a suggbeamestion of smiling (as in the face of the moon).

(a)  

This means the night-time, and it also plays on the mentions of the sea.

(a)