"Break, Break, Break" is not a free verse poem. Free verse is characterized by a lack of meter, rhyme, or rhythm; it can be composed of single lines, verses, or a block of text, but it is not deliberately structured by any rules of poetry. Free verse can use these rules, but is not governed by them. For example, William Carlos Williams wrote classic examples of free verse poetry:
"This Is Just To Say"
by William Carlos Williams
I have eaten
that were in
you were probably
they were delicious
and so cold
In this example, free verse is characterized by lack of rhyme and meter, although each stanza is structured by four lines.
"Break, Break, Break," however, has form, meter, and rhyme. Tenneyson uses "irregular quatrains" which means: the meter of the poem is not regular, that is, the syllables and rhythms are not regular, but almost random, and the poem is four verses of four lines each. Despite the irregularity of the meter, the poem is not free verse since it is specifically designed to read in a certain way; the syllable choices are not random, only unequal.
Break, break, break,
On thy cold gray stones, O Sea!
And I would that my tongue could utter
The thoughts that arise in me.
O, well for the fisherman's boy,
That he shouts with his sister at play!
O, well for the sailor lad,
That he sings in his boat on the bay!
The first stanza shows the ABCB rhyme pattern of the poem, and also shows how the syllable scheme is broken up; while the two lines rhyme, they are not syllabically consistent. The second stanza, following the ABCB format, has a more consistent syllabic rhythm; it is easier read with rhythm and intonation than the first stanza. The rhyme scheme is consistent throughout, as is the general structure. This makes the poem mostly easy to read in an iambic style, although the irregular syllabic structure makes it easy to have the rhythm interrupted.
Because of the adherence to these rules throughout, "Break, Break, Break" cannot be considered a free verse poem.