also: ひとかたまり
Refers to a single cohesive mass or a group of people/things gathered together. Often used with counters or in descriptive phrases.
The sugar has formed one lump.
The tourists are walking in one group.
Standard kanji spelling for the reading ひとかたまり.
Rare reading; ひとかたまり is overwhelmingly more common.
Kana spelling is common when the kanji reading might be ambiguous or for emphasis.
Compound of 一 (ひと, 'one') + 塊 (かたまり, 'lump, mass'). The reading いっかい is a less common on'yomi variant.