кютам

Unclear. If native, then probably inherited from Proto-Slavic *ťutati (“to keep an eye on”).

Alternatively:

• M. Filipova-Bajrova: Borrowed from Greek κοίτομαι (koítomai, “to lie down”).
• Mladenov: Influenced by Ottoman Turkish كوذماك (güdmek, “to graze, await”), via semantic shift “to graze → to tend, to overwatch → to be alert”.

кю́там • (kjútam) first-singular present indicative, impf (perfective кю́тна)

1. (dialectal, intransitive) to be alert, still
2. (reflexive with си) to keep one's mouth shut, to be quiet

• кю́тя (kjútja), кю́тим (kjútim) (i-conjugation, Western dialects)

• Georgiev, Vladimir I., editor (1986), “кютам¹”, in Български етимологичен речник [Bulgarian Etymological Dictionary] (in Bulgarian), volume 3 (крес¹ – мѝнго¹), Sofia: Bulgarian Academy of Sciences Pubg. House, page 256
• Nayden Gerov (1897) “кютѭ, -ишь”, in Рѣчникъ на Блъгарскꙑй язꙑкъ. Съ тлъкувание рѣчи-тꙑ на Блъгарскꙑ и на Русскꙑ. [Dictionary of the Bulgarian language]‎ (in Bulgarian), volume 2, Plovdiv: Дружествена печꙗтница "Съгласие.", page 443

Probably expressive from the onomatopoeia кют (kjut, “clap, bang”) +‎ -ам (-am).

кю́там • (kjútam) first-singular present indicative, impf

1. (dialectal, transitive) to pound, to pummel, to tramp

   Synonyms: у́дрям (údrjam), кату́рвам (katúrvam)

• Georgiev, Vladimir I., editor (1986), “кютам²”, in Български етимологичен речник [Bulgarian Etymological Dictionary] (in Bulgarian), volume 3 (крес¹ – мѝнго¹), Sofia: Bulgarian Academy of Sciences Pubg. House, page 256