shorthanded; undermanned
Describes a situation where there are not enough people to handle the work or task.
We are shorthanded today, so responses are delayed.
A burglar broke in when security was undermanned.
insufficient; in short supply; low
Used for stock, money, resources, or anything that is lacking in quantity.
We can't go ahead with the new project because funds are insufficient.
The stock of goods is running low.
Security at this building gets thin at night.
Stock of the popular item is running low.
The burglar targeted the poorly guarded back door.
The project's funds are starting to run short.
人手不足 spells out 'labor shortage' explicitly, whereas 手薄 is a shorter, slightly softer way to say a place or team is shorthanded.
欠乏 is a formal, often technical word for a lack of something (like nutrients or funds), while 手薄 is more everyday and often describes staffing or stock running thin.
希薄 shares the kanji 薄 with 手薄 but means 'diluted' or 'thin in concentration/spirit' (as in 希薄な意識), not a shortage of people or goods.
Compound of 手 (hand, worker) and 薄 (thin, weak), literally 'thin-handed'. The exact historical derivation is uncertain, but the meaning has been extended from lack of people to lack of resources.