In one sentence
A lender's binding agreement to make a loan on stated terms once the listed conditions are satisfied.
The longer version
Where a term sheet proposes, a commitment binds. The commitment letter fixes the terms and lists conditions precedent to funding, and issuing it typically means the loan has cleared credit approval.
The conditions in the commitment are the closing checklist in embryo. Reading them against the actual request list at kickoff prevents the late discovery that a required item was never asked for.
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