crawler

Etymology 1

From crawl (“to move slowly, by dragging the body along the ground”) + -er.

noun

1. A child who is able to creep using its hands and knees but is not able to walk.
2. (sports) A crawl swimmer.
3. A tractor crawler, a motorized vehicle that uses caterpillar tracks instead of wheels.
4. (Internet) A software bot that autonomously follows connected paths such as links between web pages.
   Crawler-based search engines have three major elements. The first is the spider, also called the crawler, which visits a web page, reads it, and then follows links to other pages within the site. 2008, Alex Michael, Ben Salter, Marketing Through Search Optimization, Routledge, page xii
   These serve as an algorithmic way to judge the “mobileness” of a site, and similar algorithms are likely to be used by the search crawlers. 2011, James Pearce, Professional Mobile Web Development with WordPress, Joomla! and Drupal, page 466
5. A mobile stage in the development of stationary hemipteran insects such as scale insects—generally the first instar.

Etymology 2

From crawl (“to act in a servile manner”) + -er. From the Australian convict period (1788–1850); a prisoner who was purposely and extensively abused by an overseer (also a convict) and thereby driven to escape but who, finding it impossible to survive in the Australian bush, surrenders to this overseer, who would then have his penal term reduced. The particular crawler was picked for his weak personality and might escape and return a number of times increasing his own penal term each time. According to James Tucker, some convict overseers had their sentences extensively reduced using this odious practice.

noun

1. (Australia, obsolete) A person who is abused, physically or verbally, and returns to the abuser a supplicant.
2. (UK, Australia, slang) A sycophant.