
Filch
Colloquial Usage
Filch is usually used in casual or informal speech rather than in formal writing. 
Petty Theft
Use 'filch' for small, often insignificant acts of theft, not for grand or serious thefts. 
Slight Negative Connotation
While 'filch' implies wrongdoing, it's often perceived as less serious or malicious than stronger theft terms. 