'Submit' is Latin for 'place under' — from 'sub-' + 'mittere' (to send). Yielding by going below.
To yield or surrender oneself to the authority or will of another; also, to present something for consideration or judgment.
From Latin 'submittere' (to lower, to let down, to yield, to reduce), composed of the prefix 'sub-' (under, beneath, up from below) and 'mittere' (to send, to release, to let go). The PIE root of 'mittere' is *meyth₂- (to exchange, to change, to go). The original concrete sense of 'submittere' was physical: to lower something, as a mast or standard. This extended to the sense of yielding authority to a superior — a general submitting to a commander — and then to the administrative and legal uses familiar today: submitting a document, a petition, a claim. The Latin prefix 'sub-' adds a spatial and hierarchical dimension: what is submitted is sent downward to