fathom
FATH-umverbMeaning to understand something fully, after much thought
Memory hook FATHOM: get to the BOTTOM of it. Sailors once lowered a weighted rope to find the depth of the sea in fathoms. To fathom a mystery is to get all the way to the bottom of it.
Pip could not fathom why anyone would put pineapple on a pancake.
In context Scientists are still trying to fathom how the birds find their way home across thousands of miles of open ocean.
Similar understand, comprehend, grasp, figure out
Opposite misunderstand
From Old English fæðm, “outstretched arms”; a fathom became a unit of six feet for measuring the depth of water, and to fathom came to mean to get to the bottom of something.