by

1. Indicates the person or thing that does or causes something: Through the action or presence of.Examples: "I was aghast by what I saw."; "In other directions the fields and sky were so much of one colour by the snow that it was difficult in a hasty glance to tell whereabouts the horizon occurred […]."

2. (with the) Acted on in units of the specified size or measure. (Sometimes hyperbolically)Examples: "sold by the yard; cheaper if bought by the gross"; "While sitting listening to the radio by the hour, she can drink brandy by the bucketful!"; "He sits listening to the radio by the hour."

3. (mathematics) multiplied by or (chiefly South Asia) divided by

4. (horse breeding) Designates a horse's male parent (sire); cf. out of.Examples: "She's a lovely little filly, by Big Lad, out of Damsel in Distress."

5. (chiefly Yeshivish) At, with, amongExamples: "Are you eating by Rabbi Fischer? (at the house of)"; "By Chabad, it's different. (with, among)"

6. (nautical) in a windward direction, sailing near to the direction from which the wind is blowing