slatter

From English dialectal slat (“to throw or dash about”), from Middle English sclatten, skleatten (“to flap”), from Old English slǣtan (“to sleat, slate”) and/or Old Norse sletta (“to slap, dash”) +‎ -er.

slatter (third-person singular simple present slatters, present participle slattering, simple past and past participle slattered) (intransitive)

1. To be awkward, careless, or negligent, especially with regard to dress and neatness.
2. To be wasteful.
   • 1768, J[ohn] Ray, “[A Collection of English Words Not Generally Used.] South and East Country Words.”, in A Compleat Collection of English Proverbs: […], 4th edition, London: […] W. Otridge, […], →OCLC, page 87:

     A ſoſſe-bangle; a ſluttiſh, ſlattering, lazy VVench, a ruſtic VVord, only uſed by the Vulgar.

• slattery
• slattern

• startle, Statler, rattles, Stalter, tatlers, starlet, telstar