Several derivations of the surname Sackett have been proposed:

• descent from Adam le Sackere, a "sacker" and exporter of wool, whose ancestors came to England with William the Conqueror;
• Roman archers, from the Latin Sagittarius, an arrow;
• manufacturer of sacks, being a diminutive of either Old English sacc or Norse-Viking Sekkr;
• a nickname from Middle English sa(c)ket ‘small sack, purse’, perhaps for a maker of purses (Oxford Dictionary of Family Names, 2016);
• an "adversary", from French Sacquet and Old German Sacco, meaning to dispute, strive, blame;
• a "cottager by the sea", the early form "Saket" meaning "sea", then pronounced "say", and "cot", on the analogy of Beckett, "bee" and "cot" indicating a cottager who kept bees.

The word "sacket" has two dictionary definitions: a bag; and a term of reproach or abuse.

None of these possible derivations of the surname is likely. Any would have resulted in the name arising independently in different places; but such is the concentration of the name in early records in a small area of Thanet that it may be supposed that the name originated in a single family. Certainly, the surname, first found in 1317, is seen to predate the earliest recorded use (c1440) of the word "sakett" meaning a bag.