Definition: i.e., useless. Shakespeare uses the word seventeen times in the plays. Compare the sonnet to Othello:
The robb'd that smiles steals something from the thief;
He robs himself that spends a bootless grief. (1.3.225)
Compare also to Titus Andronicus:
For they have fought for Rome, and all in vain;
And they have nursed this woe, in feeding life;
In bootless prayer have they been held up,
And they have served me to effectless use:
Now all the service I require of them
Is that the one will help to cut the other. (3.1.75)
Interestingly, the phrase "bootless cries" appears in Edward III, an anonymous play that many now believe Shakespeare wrote.
