Through which he slow him-self, for wrecchednesse.
(Chaucer, "The Monk's Tale")

The Old French ballade and the Italian ottava rima are considered the most direct influences on Spenser (as on Chaucer earlier when he traveled Europe in the service of the court). The Olde French ballade was also eight lines and had an ababbcbc rhyme scheme exactly like Chaucer's (or rather Chaucer's was exactly like the Old French ballade). The Italian ottava rima is also eight lines though the rhyme scheme is dissimilar to the others: abababcc. It shows its influence on Spenser's ninth line:

• Spenserian stanza: abab bcbc c
• Chaucer: abab bcbc
• Olde French ballade: abab bcbc
• Italian octava rima: abab abcc

Spenser's ninth line is identified in English prosody as iambic hexameter (hexameter is Latin for "six"). It has six stressed beats, as in this early line from The Faerie Queene:

As one^ for knight^ -ly jousts^ // and fierce^ en -count^ -ers fitt^.

Like much of English poetry, Chaucer employs a pause in the midst of the line. A pause of this sort is called a caesura and is borrowed from Old English and Old French traditions, for example, Beowulf. The pause, or caesura, is indicated above by two backslashes //. A line in iambic hexameter is not measured by syllables (though some do incorrectly try syllabic counts).

English prosody is measured by rhythmic beats, as is the ninth line in the Spenserian stanza. The reason is that English employs both pause and elision, where words are blended together ('tis = it is blended) or truncated (heav'n i' th' ev'n = heaven in the even, or evening). Thus beats (stresses) are used for scansion, not syllables.

The Old French ballade line of six iambic repetitions is called the alexandrine. It has some difference from the English iambic hexameter line. For one thing, the alexandrine is counted as syllables because French is an unstressed language with every syllable carrying the same stress as the others. It also has two major poetic accents and two minor ones. This contrasts with the six rhythmic stresses of iambic hexameter: 4 French stresses to 6 English. Yet both employ a medial caesura (mid-way pause).

With these differences and one similarity in mind, it is poetic convention to call Spenser's ninth line an alexandrine because the two line forms are similar in principle. Thus the Spenserian stanza is eight lines of iambic pentameter and one Spenserian alexandrine--with a medial caesura, six rhythm-based stresses, and no syllabic count--in the rhyme scheme ababbcbcc. The rhyme scheme is "linked," or concatenated, at the bb repetition and the cc repetition.